Merge branch 'master' into patch-1

85 files changed, 2231 insertions, 1335 deletions

diff --git a/.bumpversion.cfg b/.bumpversion.cfg
index 40db5b03..ef8a3877 100644
--- a/.bumpversion.cfg
+++ b/.bumpversion.cfg
@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 41.6.0
+current_version = 45.1.0
 commit = True
 tag = True
 
diff --git a/.flake8 b/.flake8
new file mode 100644
index 00000000..c6580616
--- /dev/null
+++ b/.flake8
@@ -0,0 +1,12 @@
+[flake8]
+exclude=
+    .tox
+    setuptools/_vendor,
+    pkg_resources/_vendor
+ignore =
+    # W503 violates spec https://github.com/PyCQA/pycodestyle/issues/513
+    W503
+    # W504 has issues https://github.com/OCA/maintainer-quality-tools/issues/545
+    W504
+    setuptools/site-patch.py F821
+    setuptools/py*compat.py F811
diff --git a/.github/workflows/python-tests.yml b/.github/workflows/python-tests.yml
new file mode 100644
index 00000000..8941b359
--- /dev/null
+++ b/.github/workflows/python-tests.yml
@@ -0,0 +1,71 @@
+name: Test suite
+
+on:
+  push:
+  pull_request:
+  schedule:
+  - cron: 1 0 * * *  # Run daily at 0:01 UTC
+
+jobs:
+  tests:
+    name: 👷
+    runs-on: ${{ matrix.os }}
+    strategy:
+      # max-parallel: 5
+      matrix:
+        python-version:
+        - 3.8
+        - 3.7
+        - 3.6
+        - 3.5
+        os:
+        - ubuntu-18.04
+        - ubuntu-16.04
+        - macOS-latest
+        # - windows-2019
+        # - windows-2016
+        env:
+        - TOXENV: python
+
+    steps:
+    - uses: actions/checkout@master
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v1
+      with:
+        version: ${{ matrix.python-version }}
+    - name: Upgrade pip/setuptools/wheel
+      run: >-
+        python
+        -m pip install
+        --disable-pip-version-check
+        --upgrade
+        pip setuptools wheel
+    - name: Install tox
+      run: >-
+        python -m pip install --upgrade tox tox-venv
+    - name: Log installed dists
+      run: >-
+        python -m pip freeze --all
+    - name: Log env vars
+      run: >-
+        env
+      env: ${{ matrix.env }}
+
+    - name: Verify that there's no cached Python modules in sources
+      if: >-
+        ! startsWith(matrix.os, 'windows-')
+      run: >-
+        ! grep pyc setuptools.egg-info/SOURCES.txt
+
+    - name: 'Initialize tox envs: ${{ matrix.env.TOXENV }}'
+      run: |
+        python -m tox --parallel auto --notest --skip-missing-interpreters false
+      env: ${{ matrix.env }}
+    - name: Test with tox
+      run: |
+        ${{ startsWith(matrix.os, 'windows-') && 'setx NETWORK_REQUIRED ' || 'export NETWORK_REQUIRED=' }}1
+        python -m tox \
+        --parallel 0 \
+        -- \
+        --cov
+      env: ${{ matrix.env }}
diff --git a/.travis.yml b/.travis.yml
index 7088d166..fe875ab6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,16 +6,13 @@ jobs:
   include:
   - &latest_py2
     python: 2.7
+    env: TOXENV=py27
   - <<: *latest_py2
-    env: LANG=C
-  - python: pypy
-    env: DISABLE_COVERAGE=1  # Don't run coverage on pypy (too slow).
+    env: LANG=C TOXENV=py27
   - python: pypy3
-    env: DISABLE_COVERAGE=1
-  - python: 3.4
+    env: DISABLE_COVERAGE=1  # Don't run coverage on pypy (too slow).
   - python: 3.5
-  - &default_py
-    python: 3.6
+  - python: 3.6
   - python: 3.7
   - &latest_py3
     python: 3.8
@@ -24,26 +21,11 @@ jobs:
   - python: 3.8-dev
   - <<: *latest_py3
     env: TOXENV=docs DISABLE_COVERAGE=1
-  - <<: *default_py
-    stage: deploy (to PyPI for tagged commits)
+  - <<: *latest_py3
+    stage: deploy
     if: tag IS present
-    install: skip
-    script: skip
-    after_success: true
-    before_deploy:
-      - python bootstrap.py
-      - "! grep pyc setuptools.egg-info/SOURCES.txt"
-    deploy:
-      provider: pypi
-      on:
-        tags: true
-        all_branches: true
-      user: __token__
-      password:
-        secure: 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
-      distributions: release
-      skip_cleanup: true
-      skip_upload_docs: true
+    script: tox -e release
+    after_success: skip
 
 cache: pip
 
@@ -58,8 +40,6 @@ install:
 - pip freeze --all
 - env
 
-# update egg_info based on setup.py in checkout
-- python bootstrap.py
 - "! grep pyc setuptools.egg-info/SOURCES.txt"
 
 script:
diff --git a/CHANGES.rst b/CHANGES.rst
index ba7b4647..198854fc 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,3 +1,64 @@
+v45.1.0
+-------
+
+* #1458: Add minimum sunset date and preamble to Python 2 warning.
+* #1704: Set sys.argv[0] in setup script run by build_meta.__legacy__
+* #1974: Add Python 3 Only Trove Classifier and remove universal wheel declaration for more complete transition from Python 2.
+
+
+v45.0.0
+-------
+
+* #1458: Drop support for Python 2. Setuptools now requires Python 3.5 or later. Install setuptools using pip >=9 or pin to Setuptools <45 to maintain 2.7 support.
+* #1959: Fix for Python 4: replace unsafe six.PY3 with six.PY2
+
+
+v44.0.0
+-------
+
+* #1908: Drop support for Python 3.4.
+
+
+v43.0.0
+-------
+
+* #1634: Include ``pyproject.toml`` in source distribution by default. Projects relying on the previous behavior where ``pyproject.toml`` was excluded by default should stop relying on that behavior or add ``exclude pyproject.toml`` to their MANIFEST.in file.
+* #1927: Setuptools once again declares 'setuptools' in the ``build-system.requires`` and adds PEP 517 build support by declaring itself as the ``build-backend``. It additionally specifies ``build-system.backend-path`` to rely on itself for those builders that support it.
+
+
+v42.0.2
+-------
+
+* #1921: Fix support for easy_install's ``find-links`` option in ``setup.cfg``.
+* #1922: Build dependencies (setup_requires and tests_require) now install transitive dependencies indicated by extras.
+
+
+v42.0.1
+-------
+
+* #1918: Fix regression in handling wheels compatibility tags.
+
+
+v42.0.0
+-------
+
+* #1830, #1909: Mark the easy_install script and setuptools command as deprecated, and use `pip <https://pip.pypa.io/en/stable/>`_ when available to fetch/build wheels for missing ``setup_requires``/``tests_require`` requirements, with the following differences in behavior:
+   * support for ``python_requires``
+   * better support for wheels (proper handling of priority with respect to PEP 425 tags)
+   * PEP 517/518 support
+   * eggs are not supported
+   * no support for the ``allow_hosts`` easy_install option (``index_url``/``find_links`` are still honored)
+   * pip environment variables are honored (and take precedence over easy_install options)
+* #1898: Removed the "upload" and "register" commands in favor of `twine <https://pypi.org/p/twine>`_.
+* #1767: Add support for the ``license_files`` option in ``setup.cfg`` to automatically
+  include multiple license files in a source distribution.
+* #1829: Update handling of wheels compatibility tags:
+  * add support for manylinux2010
+  * fix use of removed 'm' ABI flag in Python 3.8 on Windows
+* #1861: Fix empty namespace package installation from wheel.
+* #1877: Setuptools now exposes a new entry point hook "setuptools.finalize_distribution_options", enabling plugins like `setuptools_scm <https://pypi.org/project/setuptools_scm>`_ to configure options on the distribution at finalization time.
+
+
 v41.6.0
 -------
 
diff --git a/README.rst b/README.rst
index dac8a468..da0549a9 100644
--- a/README.rst
+++ b/README.rst
@@ -34,8 +34,17 @@ To report a security vulnerability, please use the
 Tidelift will coordinate the fix and disclosure.
 
 
+For Enterprise
+==============
+
+Available as part of the Tidelift Subscription.
+
+Setuptools and the maintainers of thousands of other packages are working with Tidelift to deliver one enterprise subscription that covers all of the open source you use.
+
+`Learn more <https://tidelift.com/subscription/pkg/pypi-setuptools?utm_source=pypi-setuptools&utm_medium=referral&utm_campaign=github>`_.
+
 Code of Conduct
----------------
+===============
 
 Everyone interacting in the setuptools project's codebases, issue trackers,
 chat rooms, and mailing lists is expected to follow the
diff --git a/appveyor.yml b/appveyor.yml
index 08818069..f7ab22f6 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -9,8 +9,8 @@ environment:
   matrix:
     - APPVEYOR_JOB_NAME: "python36-x64"
       PYTHON: "C:\\Python36-x64"
-    - APPVEYOR_JOB_NAME: "python27-x64"
-      PYTHON: "C:\\Python27-x64"
+    - APPVEYOR_JOB_NAME: "python37-x64"
+      PYTHON: "C:\\Python37-x64"
 
 install:
   # symlink python from a directory with a space
@@ -28,7 +28,6 @@ test_script:
   - python -m pip install --disable-pip-version-check --upgrade pip setuptools wheel
   - pip install --upgrade tox tox-venv virtualenv
   - pip freeze --all
-  - python bootstrap.py
   - tox -- --cov
 
 after_test:
diff --git a/azure-pipelines.yml b/azure-pipelines.yml
new file mode 100644
index 00000000..3e80bf44
--- /dev/null
+++ b/azure-pipelines.yml
@@ -0,0 +1,71 @@
+# Create the project in Azure with:
+# az devops project create --name $name --organization https://dev.azure.com/$org/ --visibility public
+# then configure the pipelines (through web UI)
+
+trigger:
+  branches:
+    include:
+    - '*'
+  tags:
+    include:
+    - '*'
+
+pool:
+  vmimage: 'Ubuntu-18.04'
+
+variables:
+- group: Azure secrets
+
+stages:
+- stage: Test
+  jobs:
+
+  - job: 'Test'
+    strategy:
+      matrix:
+        Python36:
+          python.version: '3.6'
+        Python38:
+          python.version: '3.8'
+      maxParallel: 4
+
+    steps:
+    - task: UsePythonVersion@0
+      inputs:
+        versionSpec: '$(python.version)'
+        architecture: 'x64'
+
+    - script: python -m pip install tox
+      displayName: 'Install tox'
+
+    - script: |
+        tox -- --junit-xml=test-results.xml
+      displayName: 'run tests'
+
+    - task: PublishTestResults@2
+      inputs:
+        testResultsFiles: '**/test-results.xml'
+        testRunTitle: 'Python $(python.version)'
+      condition: succeededOrFailed()
+
+- stage: Publish
+  dependsOn: Test
+  jobs:
+  - job: 'Publish'
+
+    steps:
+    - task: UsePythonVersion@0
+      inputs:
+        versionSpec: '3.8'
+        architecture: 'x64'
+
+    - script: python -m pip install tox
+      displayName: 'Install tox'
+
+    - script: |
+        tox -e release
+      env:
+        TWINE_PASSWORD: $(PyPI-token)
+      displayName: 'publish to PyPI'
+
+  condition: contains(variables['Build.SourceBranch'], 'tags')
diff --git a/bootstrap.py b/bootstrap.py
index 8c7d7fc3..8fa9e4b5 100644
--- a/bootstrap.py
+++ b/bootstrap.py
@@ -25,6 +25,7 @@ minimal_egg_info = textwrap.dedent("""
     entry_points = setuptools.dist:check_entry_points
 
     [egg_info.writers]
+    PKG-INFO = setuptools.command.egg_info:write_pkg_info
     dependency_links.txt = setuptools.command.egg_info:overwrite_arg
     entry_points.txt = setuptools.command.egg_info:write_entries
     requires.txt = setuptools.command.egg_info:write_requirements
@@ -35,10 +36,11 @@ def ensure_egg_info():
     if os.path.exists('setuptools.egg-info'):
         return
     print("adding minimal entry_points")
-    build_egg_info()
+    add_minimal_info()
+    run_egg_info()
 
 
-def build_egg_info():
+def add_minimal_info():
     """
     Build a minimal egg-info, enough to invoke egg_info
     """
@@ -52,13 +54,6 @@ def run_egg_info():
     cmd = [sys.executable, 'setup.py', 'egg_info']
     print("Regenerating egg_info")
     subprocess.check_call(cmd)
-    print("...and again.")
-    subprocess.check_call(cmd)
-
-
-def main():
-    ensure_egg_info()
-    run_egg_info()
 
 
-__name__ == '__main__' and main()
+__name__ == '__main__' and ensure_egg_info()
diff --git a/changelog.d/1861.change.rst b/changelog.d/1861.change.rst
deleted file mode 100644
index 5a4e0a56..00000000
--- a/changelog.d/1861.change.rst
+++ /dev/null
@@ -1 +0,0 @@
-Fix empty namespace package installation from wheel.
diff --git a/changelog.d/1898.breaking.rst b/changelog.d/1898.breaking.rst
deleted file mode 100644
index 844a8a42..00000000
--- a/changelog.d/1898.breaking.rst
+++ /dev/null
@@ -1 +0,0 @@
-Removed the "upload" and "register" commands in favor of `twine <https://pypi.org/p/twine>`_.
diff --git a/changelog.d/1968.misc.rst b/changelog.d/1968.misc.rst
new file mode 100644
index 00000000..4aa5343f
--- /dev/null
+++ b/changelog.d/1968.misc.rst
@@ -0,0 +1 @@
+Add flake8-2020 to check for misuse of sys.version or sys.version_info.
diff --git a/docs/_templates/indexsidebar.html b/docs/_templates/indexsidebar.html
index 504de6b0..d803b8a3 100644
--- a/docs/_templates/indexsidebar.html
+++ b/docs/_templates/indexsidebar.html
@@ -1,3 +1,10 @@
+<h3 class="donation">For Enterprise</h3>
+
+<p>
+Professionally-supported {{ project }} is available with the
+<a href="https://tidelift.com/subscription/pkg/pypi-{{ project }}?utm_source=pypi-{{ project }}&utm_medium=referral">Tidelift Subscription</a>.
+</p>
+
 <h3>Download</h3>
 
 <p>Current version: <b>{{ version }}</b></p>
@@ -6,10 +13,3 @@
 <h3>Questions? Suggestions? Contributions?</h3>
 
 <p>Visit the <a href="{{ package_url }}">Project page</a> </p>
-
-<h3 class="donation">Professional support</h3>
-
-<p>
-Professionally-supported {{ project }} is available with the
-<a href="https://tidelift.com/subscription/pkg/pypi-{{ project }}?utm_source=pypi-{{ project }}&utm_medium=readme">Tidelift Subscription</a>.
-</p>
diff --git a/docs/conf.py b/docs/conf.py
index cbd19fb4..b92b50cc 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -1,23 +1,3 @@
-# -*- coding: utf-8 -*-
-#
-# Setuptools documentation build configuration file, created by
-# sphinx-quickstart on Fri Jul 17 14:22:37 2009.
-#
-# This file is execfile()d with the current directory set to its containing dir.
-#
-# The contents of this file are pickled, so don't put values in the namespace
-# that aren't pickleable (module imports are okay, they're removed automatically).
-#
-# Note that not all possible configuration values are present in this
-# autogenerated file.
-#
-# All configuration values have a default; values that are commented out
-# serve to show the default
-
-# If extensions (or modules to document with autodoc) are in another directory,
-# add these directories to sys.path here. If the directory is relative to the
-# documentation root, use os.path.abspath to make it absolute, like shown here.
-
 import subprocess
 import sys
 import os
@@ -26,14 +6,12 @@ import os
 # hack to run the bootstrap script so that jaraco.packaging.sphinx
 # can invoke setup.py
 'READTHEDOCS' in os.environ and subprocess.check_call(
-    [sys.executable, 'bootstrap.py'],
+    [sys.executable, '-m', 'bootstrap'],
     cwd=os.path.join(os.path.dirname(__file__), os.path.pardir),
 )
 
-# -- General configuration -----------------------------------------------------
+# -- General configuration --
 
-# Add any Sphinx extension module names here, as strings. They can be extensions
-# coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
 extensions = ['jaraco.packaging.sphinx', 'rst.linker']
 
 # Add any paths that contain templates here, relative to this directory.
@@ -45,7 +23,8 @@ source_suffix = '.txt'
 # The master toctree document.
 master_doc = 'index'
 
-# A list of glob-style patterns that should be excluded when looking for source files.
+# A list of glob-style patterns that should be excluded
+# when looking for source files.
 exclude_patterns = ['requirements.txt']
 
 # List of directories, relative to source directory, that shouldn't be searched
@@ -55,7 +34,7 @@ exclude_trees = []
 # The name of the Pygments (syntax highlighting) style to use.
 pygments_style = 'sphinx'
 
-# -- Options for HTML output ---------------------------------------------------
+# -- Options for HTML output --
 
 # The theme to use for HTML and HTML Help pages.  Major themes that come with
 # Sphinx are currently 'default' and 'sphinxdoc'.
@@ -69,7 +48,10 @@ html_theme_path = ['_theme']
 html_use_smartypants = True
 
 # Custom sidebar templates, maps document names to template names.
-html_sidebars = {'index': ['relations.html', 'sourcelink.html', 'indexsidebar.html', 'searchbox.html']}
+html_sidebars = {
+    'index': [
+        'relations.html', 'sourcelink.html', 'indexsidebar.html',
+        'searchbox.html']}
 
 # If false, no module index is generated.
 html_use_modindex = False
@@ -77,14 +59,15 @@ html_use_modindex = False
 # If false, no index is generated.
 html_use_index = False
 
-# -- Options for LaTeX output --------------------------------------------------
+# -- Options for LaTeX output --
 
 # Grouping the document tree into LaTeX files. List of tuples
-# (source start file, target name, title, author, documentclass [howto/manual]).
-latex_documents = [
-  ('index', 'Setuptools.tex', 'Setuptools Documentation',
-   'The fellowship of the packaging', 'manual'),
-]
+# (source start file, target name, title, author,
+# documentclass [howto/manual]).
+latex_documents = [(
+    'index', 'Setuptools.tex', 'Setuptools Documentation',
+    'The fellowship of the packaging', 'manual',
+)]
 
 link_files = {
     '../CHANGES.rst': dict(
diff --git a/docs/developer-guide.txt b/docs/developer-guide.txt
index d145fba1..0b4ae4d4 100644
--- a/docs/developer-guide.txt
+++ b/docs/developer-guide.txt
@@ -104,12 +104,8 @@ from the command line after pushing a new branch.
 Testing
 -------
 
-The primary tests are run using tox. To run the tests, first create the metadata
-needed to run the tests::
-
-    $ python bootstrap.py
-
-Then make sure you have tox installed, and invoke it::
+The primary tests are run using tox.  Make sure you have tox installed,
+and invoke it::
 
     $ tox
 
diff --git a/docs/easy_install.txt b/docs/easy_install.txt
index 544b9efd..fac7b8fc 100644
--- a/docs/easy_install.txt
+++ b/docs/easy_install.txt
@@ -41,7 +41,7 @@ Please see the `setuptools PyPI page <https://pypi.org/project/setuptools/>`_
 for download links and basic installation instructions for each of the
 supported platforms.
 
-You will need at least Python 3.4 or 2.7.  An ``easy_install`` script will be
+You will need at least Python 3.5 or 2.7.  An ``easy_install`` script will be
 installed in the normal location for Python scripts on your platform.
 
 Note that the instructions on the setuptools PyPI page assume that you are
diff --git a/docs/setuptools.txt b/docs/setuptools.txt
index 399a56d3..f84837ff 100644
--- a/docs/setuptools.txt
+++ b/docs/setuptools.txt
@@ -62,7 +62,7 @@ Installing ``setuptools``
 
 To install the latest version of setuptools, use::
 
-    pip install -U setuptools
+    pip install --upgrade setuptools
 
 Refer to `Installing Packages`_ guide for more information.
 
@@ -88,7 +88,7 @@ packages in the directory where the setup.py lives.  See the `Command
 Reference`_ section below to see what commands you can give to this setup
 script. For example, to produce a source distribution, simply invoke::
 
-    python setup.py sdist
+    setup.py sdist
 
 Of course, before you release your project to PyPI, you'll want to add a bit
 more information to your setup script to help people find or learn about your
@@ -100,17 +100,17 @@ dependencies, and perhaps some data files and scripts::
         name="HelloWorld",
         version="0.1",
         packages=find_packages(),
-        scripts=['say_hello.py'],
+        scripts=["say_hello.py"],
 
         # Project uses reStructuredText, so ensure that the docutils get
         # installed or upgraded on the target machine
-        install_requires=['docutils>=0.3'],
+        install_requires=["docutils>=0.3"],
 
         package_data={
             # If any package contains *.txt or *.rst files, include them:
-            '': ['*.txt', '*.rst'],
-            # And include any *.msg files found in the 'hello' package, too:
-            'hello': ['*.msg'],
+            "": ["*.txt", "*.rst"],
+            # And include any *.msg files found in the "hello" package, too:
+            "hello": ["*.msg"],
         },
 
         # metadata to display on PyPI
@@ -125,7 +125,7 @@ dependencies, and perhaps some data files and scripts::
             "Source Code": "https://code.example.com/HelloWorld/",
         },
         classifiers=[
-            'License :: OSI Approved :: Python Software Foundation License'
+            "License :: OSI Approved :: Python Software Foundation License"
         ]
 
         # could also include long_description, download_url, etc.
@@ -207,11 +207,11 @@ but here are a few tips that will keep you out of trouble in the corner cases:
   to compare different version numbers::
 
     >>> from pkg_resources import parse_version
-    >>> parse_version('1.9.a.dev') == parse_version('1.9a0dev')
+    >>> parse_version("1.9.a.dev") == parse_version("1.9a0dev")
     True
-    >>> parse_version('2.1-rc2') < parse_version('2.1')
+    >>> parse_version("2.1-rc2") < parse_version("2.1")
     True
-    >>> parse_version('0.6a9dev-r41475') < parse_version('0.6a9')
+    >>> parse_version("0.6a9dev-r41475") < parse_version("0.6a9")
     True
 
 Once you've decided on a version numbering scheme for your project, you can
@@ -282,10 +282,11 @@ unless you need the associated ``setuptools`` feature.
 ``setup_requires``
     A string or list of strings specifying what other distributions need to
     be present in order for the *setup script* to run.  ``setuptools`` will
-    attempt to obtain these before processing the rest of the setup script or
-    commands.  This argument is needed if you are using distutils extensions as
-    part of your build process; for example, extensions that process setup()
-    arguments and turn them into EGG-INFO metadata files.
+    attempt to obtain these (using pip if available) before processing the
+    rest of the setup script or commands.  This argument is needed if you
+    are using distutils extensions as part of your build process; for
+    example, extensions that process setup() arguments and turn them into
+    EGG-INFO metadata files.
 
     (Note: projects listed in ``setup_requires`` will NOT be automatically
     installed on the system where the setup script is being run.  They are
@@ -332,10 +333,10 @@ unless you need the associated ``setuptools`` feature.
     needed to install it, you can use this option to specify them.  It should
     be a string or list of strings specifying what other distributions need to
     be present for the package's tests to run.  When you run the ``test``
-    command, ``setuptools`` will  attempt to obtain these.  Note that these
-    required projects will *not* be installed on the system where the tests
-    are run, but only downloaded to the project's setup directory if they're
-    not already installed locally.
+    command, ``setuptools`` will  attempt to obtain these (using pip if
+    available).  Note that these required projects will *not* be installed on
+    the system where the tests are run, but only downloaded to the project's setup
+    directory if they're not already installed locally.
 
     New in 41.5.0: Deprecated the test command.
 
@@ -370,7 +371,7 @@ unless you need the associated ``setuptools`` feature.
     imported.  This argument is only useful if the project will be installed as
     a zipfile, and there is a need to have all of the listed resources be
     extracted to the filesystem *as a unit*.  Resources listed here
-    should be '/'-separated paths, relative to the source root, so to list a
+    should be "/"-separated paths, relative to the source root, so to list a
     resource ``foo.png`` in package ``bar.baz``, you would include the string
     ``bar/baz/foo.png`` in this argument.
 
@@ -412,7 +413,7 @@ the same
 directory as the setup script.  Some projects use a ``src`` or ``lib``
 directory as the root of their source tree, and those projects would of course
 use ``"src"`` or ``"lib"`` as the first argument to ``find_packages()``.  (And
-such projects also need something like ``package_dir={'':'src'}`` in their
+such projects also need something like ``package_dir={"": "src"}`` in their
 ``setup()`` arguments, but that's just a normal distutils thing.)
 
 Anyway, ``find_packages()`` walks the target directory, filtering by inclusion
@@ -479,7 +480,7 @@ top-level package called ``tests``! One way to avoid this problem is to use the
     setup(
         name="namespace.mypackage",
         version="0.1",
-        packages=find_namespace_packages(include=['namespace.*'])
+        packages=find_namespace_packages(include=["namespace.*"])
     )
 
 Another option is to use the "src" layout, where all package code is placed in
@@ -499,8 +500,8 @@ With this layout, the package directory is specified as ``src``, as such::
 
     setup(name="namespace.mypackage",
           version="0.1",
-          package_dir={'': 'src'},
-          packages=find_namespace_packages(where='src'))
+          package_dir={"": "src"},
+          packages=find_namespace_packages(where="src"))
 
 .. _PEP 420: https://www.python.org/dev/peps/pep-0420/
 
@@ -525,12 +526,12 @@ script called ``baz``, you might do something like this::
     setup(
         # other arguments here...
         entry_points={
-            'console_scripts': [
-                'foo = my_package.some_module:main_func',
-                'bar = other_module:some_func',
+            "console_scripts": [
+                "foo = my_package.some_module:main_func",
+                "bar = other_module:some_func",
             ],
-            'gui_scripts': [
-                'baz = my_package_gui:start_func',
+            "gui_scripts": [
+                "baz = my_package_gui:start_func",
             ]
         }
     )
@@ -566,8 +567,8 @@ as the following::
     setup(
         # other arguments here...
         entry_points={
-            'setuptools.installation': [
-                'eggsecutable = my_package.some_module:main_func',
+            "setuptools.installation": [
+                "eggsecutable = my_package.some_module:main_func",
             ]
         }
     )
@@ -740,8 +741,8 @@ For example, let's say that Project A offers optional PDF and reST support::
         name="Project-A",
         ...
         extras_require={
-            'PDF':  ["ReportLab>=1.2", "RXP"],
-            'reST': ["docutils>=0.3"],
+            "PDF":  ["ReportLab>=1.2", "RXP"],
+            "reST": ["docutils>=0.3"],
         }
     )
 
@@ -762,9 +763,9 @@ declare it like this, so that the "PDF" requirements are only resolved if the
         name="Project-A",
         ...
         entry_points={
-            'console_scripts': [
-                'rst2pdf = project_a.tools.pdfgen [PDF]',
-                'rst2html = project_a.tools.htmlgen',
+            "console_scripts": [
+                "rst2pdf = project_a.tools.pdfgen [PDF]",
+                "rst2html = project_a.tools.htmlgen",
                 # more script entry points ...
             ],
         }
@@ -800,8 +801,8 @@ setup to this::
         name="Project-A",
         ...
         extras_require={
-            'PDF':  [],
-            'reST': ["docutils>=0.3"],
+            "PDF":  [],
+            "reST": ["docutils>=0.3"],
         }
     )
 
@@ -828,8 +829,8 @@ For example, here is a project that uses the ``enum`` module and ``pywin32``::
         name="Project",
         ...
         install_requires=[
-            'enum34;python_version<"3.4"',
-            'pywin32 >= 1.0;platform_system=="Windows"'
+            "enum34;python_version<'3.4'",
+            "pywin32 >= 1.0;platform_system=='Windows'"
         ]
     )
 
@@ -877,9 +878,9 @@ e.g.::
         ...
         package_data={
             # If any package contains *.txt or *.rst files, include them:
-            '': ['*.txt', '*.rst'],
-            # And include any *.msg files found in the 'hello' package, too:
-            'hello': ['*.msg'],
+            "": ["*.txt", "*.rst"],
+            # And include any *.msg files found in the "hello" package, too:
+            "hello": ["*.msg"],
         }
     )
 
@@ -902,15 +903,15 @@ The setuptools setup file might look like this::
     from setuptools import setup, find_packages
     setup(
         ...
-        packages=find_packages('src'),  # include all packages under src
-        package_dir={'':'src'},   # tell distutils packages are under src
+        packages=find_packages("src"),  # include all packages under src
+        package_dir={"": "src"},   # tell distutils packages are under src
 
         package_data={
             # If any package contains *.txt files, include them:
-            '': ['*.txt'],
-            # And include any *.dat files found in the 'data' subdirectory
-            # of the 'mypkg' package, also:
-            'mypkg': ['data/*.dat'],
+            "": ["*.txt"],
+            # And include any *.dat files found in the "data" subdirectory
+            # of the "mypkg" package, also:
+            "mypkg": ["data/*.dat"],
         }
     )
 
@@ -925,7 +926,7 @@ converts slashes to appropriate platform-specific separators at build time.
 
 If datafiles are contained in a subdirectory of a package that isn't a package
 itself (no ``__init__.py``), then the subdirectory names (or ``*``) are required
-in the ``package_data`` argument (as shown above with ``'data/*.dat'``).
+in the ``package_data`` argument (as shown above with ``"data/*.dat"``).
 
 When building an ``sdist``, the datafiles are also drawn from the
 ``package_name.egg-info/SOURCES.txt`` file, so make sure that this is removed if
@@ -950,18 +951,18 @@ to do things like this::
     from setuptools import setup, find_packages
     setup(
         ...
-        packages=find_packages('src'),  # include all packages under src
-        package_dir={'':'src'},   # tell distutils packages are under src
+        packages=find_packages("src"),  # include all packages under src
+        package_dir={"": "src"},   # tell distutils packages are under src
 
         include_package_data=True,    # include everything in source control
 
         # ...but exclude README.txt from all packages
-        exclude_package_data={'': ['README.txt']},
+        exclude_package_data={"": ["README.txt"]},
     )
 
 The ``exclude_package_data`` option is a dictionary mapping package names to
 lists of wildcard patterns, just like the ``package_data`` option.  And, just
-as with that option, a key of ``''`` will apply the given pattern(s) to all
+as with that option, a key of ``""`` will apply the given pattern(s) to all
 packages.  However, any files that match these patterns will be *excluded*
 from installation, even if they were listed in ``package_data`` or were
 included as a result of using ``include_package_data``.
@@ -999,11 +1000,11 @@ and Python Eggs.  It is strongly recommended that, if you are using data files,
 you should use the :ref:`ResourceManager API` of ``pkg_resources`` to access
 them.  The ``pkg_resources`` module is distributed as part of setuptools, so if
 you're using setuptools to distribute your package, there is no reason not to
-use its resource management API.  See also `Accessing Package Resources`_ for
+use its resource management API.  See also `Importlib Resources`_ for
 a quick example of converting code that uses ``__file__`` to use
 ``pkg_resources`` instead.
 
-.. _Accessing Package Resources: http://peak.telecommunity.com/DevCenter/PythonEggs#accessing-package-resources
+.. _Importlib Resources: https://docs.python.org/3/library/importlib.html#module-importlib.resources
 
 
 Non-Package Data Files
@@ -1095,12 +1096,12 @@ for our hypothetical blogging tool::
 
     setup(
         # ...
-        entry_points={'blogtool.parsers': '.rst = some_module:SomeClass'}
+        entry_points={"blogtool.parsers": ".rst = some_module:SomeClass"}
     )
 
     setup(
         # ...
-        entry_points={'blogtool.parsers': ['.rst = some_module:a_func']}
+        entry_points={"blogtool.parsers": [".rst = some_module:a_func"]}
     )
 
     setup(
@@ -1198,7 +1199,7 @@ command; see the section on the `develop`_ command below for more details.
 Note that you can also apply setuptools commands to non-setuptools projects,
 using commands like this::
 
-   python -c "import setuptools; execfile('setup.py')" develop
+   python -c "import setuptools; with open('setup.py') as f: exec(compile(f.read(), 'setup.py', 'exec'))" develop
 
 That is, you can simply list the normal setup commands and options following
 the quoted part.
@@ -1207,28 +1208,28 @@ the quoted part.
 Distributing a ``setuptools``-based project
 ===========================================
 
-Detailed instructions to distribute a setuptools project can be found at 
+Detailed instructions to distribute a setuptools project can be found at
 `Packaging project tutorials`_.
 
 .. _Packaging project tutorials: https://packaging.python.org/tutorials/packaging-projects/#generating-distribution-archives
 
 Before you begin, make sure you have the latest versions of setuptools and wheel::
 
-    python3 -m pip install --user --upgrade setuptools wheel
+    pip install --upgrade setuptools wheel
 
 To build a setuptools project, run this command from the same directory where
 setup.py is located::
 
-    python3 setup.py sdist bdist_wheel
+    setup.py sdist bdist_wheel
 
 This will generate distribution archives in the `dist` directory.
 
-Before you upload the generated archives make sure you're registered on 
+Before you upload the generated archives make sure you're registered on
 https://test.pypi.org/account/register/. You will also need to verify your email
 to be able to upload any packages.
 You should install twine to be able to upload packages::
 
-    python3 -m pip install --user --upgrade setuptools wheel
+    pip install --upgrade twine
 
 Now, to upload these archives, run::
 
@@ -1236,7 +1237,7 @@ Now, to upload these archives, run::
 
 To install your newly uploaded package ``example_pkg``,  you can use pip::
 
-    python3 -m pip install --index-url https://test.pypi.org/simple/ example_pkg
+    pip install --index-url https://test.pypi.org/simple/ example_pkg
 
 If you have issues at any point, please refer to `Packaging project tutorials`_
 for clarification.
@@ -1308,7 +1309,7 @@ participates in.  For example, the ZopeInterface project might do this::
 
     setup(
         # ...
-        namespace_packages=['zope']
+        namespace_packages=["zope"]
     )
 
 because it contains a ``zope.interface`` package that lives in the ``zope``
@@ -1326,7 +1327,7 @@ packages' ``__init__.py`` files (and the ``__init__.py`` of any parent
 packages), in a normal Python package layout.  These ``__init__.py`` files
 *must* contain the line::
 
-    __import__('pkg_resources').declare_namespace(__name__)
+    __import__("pkg_resources").declare_namespace(__name__)
 
 This code ensures that the namespace package machinery is operating and that
 the current package is registered as a namespace package.
@@ -1409,7 +1410,7 @@ pattern.  So, you can use a command line like::
 
     setup.py egg_info -rbDEV bdist_egg rotate -m.egg -k3
 
-to build an egg whose version info includes 'DEV-rNNNN' (where NNNN is the
+to build an egg whose version info includes "DEV-rNNNN" (where NNNN is the
 most recent Subversion revision that affected the source tree), and then
 delete any egg files from the distribution directory except for the three
 that were built most recently.
@@ -1468,7 +1469,7 @@ tagging the release, so the trunk will still produce development snapshots.
 Alternately, if you are not branching for releases, you can override the
 default version options on the command line, using something like::
 
-    python setup.py egg_info -Db "" sdist bdist_egg
+    setup.py egg_info -Db "" sdist bdist_egg
 
 The first part of this command (``egg_info -Db ""``) will override the
 configured tag information, before creating source and binary eggs. Thus, these
@@ -1478,11 +1479,11 @@ build designation string.
 Of course, if you will be doing this a lot, you may wish to create a personal
 alias for this operation, e.g.::
 
-    python setup.py alias -u release egg_info -Db ""
+    setup.py alias -u release egg_info -Db ""
 
 You can then use it like this::
 
-    python setup.py release sdist bdist_egg
+    setup.py release sdist bdist_egg
 
 Or of course you can create more elaborate aliases that do all of the above.
 See the sections below on the `egg_info`_ and `alias`_ commands for more ideas.
@@ -1499,7 +1500,7 @@ To ensure Cython is available, include Cython in the build-requires section
 of your pyproject.toml::
 
     [build-system]
-    requires=[..., 'cython']
+    requires=[..., "cython"]
 
 Built with pip 10 or later, that declaration is sufficient to include Cython
 in the build. For broader compatibility, declare the dependency in your
@@ -1799,7 +1800,7 @@ to support "daily builds" or "snapshot" releases.  It is run automatically by
 the ``sdist``, ``bdist_egg``, ``develop``, and ``test`` commands in order to
 update the project's metadata, but you can also specify it explicitly in order
 to temporarily change the project's version string while executing other
-commands.  (It also generates the``.egg-info/SOURCES.txt`` manifest file, which
+commands.  (It also generates the ``.egg-info/SOURCES.txt`` manifest file, which
 is used when you are building source distributions.)
 
 In addition to writing the core egg metadata defined by ``setuptools`` and
@@ -1847,7 +1848,7 @@ binary distributions of your project, you should first make sure that you know
 how the resulting version numbers will be interpreted by automated tools
 like pip.  See the section above on `Specifying Your Project's Version`_ for an
 explanation of pre- and post-release tags, as well as tips on how to choose and
-verify a versioning scheme for your your project.)
+verify a versioning scheme for your project.)
 
 For advanced uses, there is one other option that can be set, to change the
 location of the project's ``.egg-info`` directory.  Commands that need to find
@@ -1872,12 +1873,12 @@ Other ``egg_info`` Options
 
 Creating a dated "nightly build" snapshot egg::
 
-    python setup.py egg_info --tag-date --tag-build=DEV bdist_egg
+    setup.py egg_info --tag-date --tag-build=DEV bdist_egg
 
 Creating a release with no version tags, even if some default tags are
 specified in ``setup.cfg``::
 
-    python setup.py egg_info -RDb "" sdist bdist_egg
+    setup.py egg_info -RDb "" sdist bdist_egg
 
 (Notice that ``egg_info`` must always appear on the command line *before* any
 commands that you want the version changes to apply to.)
@@ -2273,6 +2274,7 @@ maintainer_email                maintainer-email   str
 classifiers                     classifier         file:, list-comma
 license                                            str
 license_file                                       str
+license_files                                      list-comma
 description                     summary            file:, str
 long_description                long-description   file:, str
 long_description_content_type                      str                38.6.0
@@ -2349,7 +2351,7 @@ parsing ``metadata`` and ``options`` sections into a dictionary.
 
     from setuptools.config import read_configuration
 
-    conf_dict = read_configuration('/home/user/dev/package/setup.cfg')
+    conf_dict = read_configuration("/home/user/dev/package/setup.cfg")
 
 
 By default, ``read_configuration()`` will read only the file provided
@@ -2417,6 +2419,10 @@ script defines entry points for them!
 Adding ``setup()`` Arguments
 ----------------------------
 
+.. warning:: Adding arguments to setup is discouraged as such arguments
+   are only supported through imperative execution and not supported through
+   declarative config.
+
 Sometimes, your commands may need additional arguments to the ``setup()``
 call.  You can enable this by defining entry points in the
 ``distutils.setup_keywords`` group.  For example, if you wanted a ``setup()``
@@ -2468,6 +2474,25 @@ script using your extension lists your project in its ``setup_requires``
 argument.
 
 
+Customizing Distribution Options
+--------------------------------
+
+Plugins may wish to extend or alter the options on a Distribution object to
+suit the purposes of that project. For example, a tool that infers the
+``Distribution.version`` from SCM-metadata may need to hook into the
+option finalization. To enable this feature, Setuptools offers an entry
+point "setuptools.finalize_distribution_options". That entry point must
+be a callable taking one argument (the Distribution instance).
+
+If the callable has an ``.order`` property, that value will be used to
+determine the order in which the hook is called. Lower numbers are called
+first and the default is zero (0).
+
+Plugins may read, alter, and set properties on the distribution, but each
+plugin is encouraged to load the configuration/settings for their behavior
+independently.
+
+
 Adding new EGG-INFO Files
 -------------------------
 
@@ -2506,7 +2531,7 @@ a file.  Here's what the writer utility looks like::
         argname = os.path.splitext(basename)[0]
         value = getattr(cmd.distribution, argname, None)
         if value is not None:
-            value = '\n'.join(value) + '\n'
+            value = "\n".join(value) + "\n"
         cmd.write_or_delete_file(argname, filename, value)
 
 As you can see, ``egg_info.writers`` entry points must be a function taking
diff --git a/pkg_resources/__init__.py b/pkg_resources/__init__.py
index 51fb1192..75563f95 100644
--- a/pkg_resources/__init__.py
+++ b/pkg_resources/__init__.py
@@ -83,13 +83,14 @@ __import__('pkg_resources.extern.packaging.version')
 __import__('pkg_resources.extern.packaging.specifiers')
 __import__('pkg_resources.extern.packaging.requirements')
 __import__('pkg_resources.extern.packaging.markers')
+__import__('pkg_resources.py2_warn')
 
 
 __metaclass__ = type
 
 
-if (3, 0) < sys.version_info < (3, 4):
-    raise RuntimeError("Python 3.4 or later is required")
+if (3, 0) < sys.version_info < (3, 5):
+    raise RuntimeError("Python 3.5 or later is required")
 
 if six.PY2:
     # Those builtin exceptions are only defined in Python 3
@@ -2328,7 +2329,8 @@ register_namespace_handler(object, null_ns_handler)
 
 def normalize_path(filename):
     """Normalize a file/dir name for comparison purposes"""
-    return os.path.normcase(os.path.realpath(os.path.normpath(_cygwin_patch(filename))))
+    return os.path.normcase(os.path.realpath(os.path.normpath(
+        _cygwin_patch(filename))))
 
 
 def _cygwin_patch(filename):  # pragma: nocover
@@ -3287,6 +3289,7 @@ def _initialize_master_working_set():
     list(map(working_set.add_entry, sys.path))
     globals().update(locals())
 
+
 class PkgResourcesDeprecationWarning(Warning):
     """
     Base class for warning about deprecations in ``pkg_resources``
diff --git a/pkg_resources/py2_warn.py b/pkg_resources/py2_warn.py
new file mode 100644
index 00000000..1b151956
--- /dev/null
+++ b/pkg_resources/py2_warn.py
@@ -0,0 +1,22 @@
+import sys
+import warnings
+import textwrap
+
+
+msg = textwrap.dedent("""
+    You are running Setuptools on Python 2, which is no longer
+    supported and
+    >>> SETUPTOOLS WILL STOP WORKING <<<
+    in a subsequent release (no sooner than 2020-04-20).
+    Please ensure you are installing
+    Setuptools using pip 9.x or later or pin to `setuptools<45`
+    in your environment.
+    If you have done those things and are still encountering
+    this message, please comment in
+    https://github.com/pypa/setuptools/issues/1458
+    about the steps that led to this unsupported combination.
+    """)
+
+pre = "Setuptools will stop working on Python 2\n"
+
+sys.version_info < (3,) and warnings.warn(pre + "*" * 60 + msg + "*" * 60)
diff --git a/pkg_resources/tests/test_pkg_resources.py b/pkg_resources/tests/test_pkg_resources.py
index 5960868a..78281869 100644
--- a/pkg_resources/tests/test_pkg_resources.py
+++ b/pkg_resources/tests/test_pkg_resources.py
@@ -17,7 +17,9 @@ try:
 except ImportError:
     import mock
 
-from pkg_resources import DistInfoDistribution, Distribution, EggInfoDistribution
+from pkg_resources import (
+    DistInfoDistribution, Distribution, EggInfoDistribution,
+)
 from setuptools.extern import six
 from pkg_resources.extern.six.moves import map
 from pkg_resources.extern.six import text_type, string_types
@@ -279,8 +281,8 @@ def make_distribution_no_version(tmpdir, basename):
         ('dist-info', 'METADATA', DistInfoDistribution),
     ],
 )
-def test_distribution_version_missing(tmpdir, suffix, expected_filename,
-    expected_dist_type):
+def test_distribution_version_missing(
+        tmpdir, suffix, expected_filename, expected_dist_type):
     """
     Test Distribution.version when the "Version" header is missing.
     """
diff --git a/pkg_resources/tests/test_resources.py b/pkg_resources/tests/test_resources.py
index 93fa7114..ed7cdfcc 100644
--- a/pkg_resources/tests/test_resources.py
+++ b/pkg_resources/tests/test_resources.py
@@ -15,7 +15,7 @@ import pkg_resources
 from pkg_resources import (
     parse_requirements, VersionConflict, parse_version,
     Distribution, EntryPoint, Requirement, safe_version, safe_name,
-    WorkingSet, PkgResourcesDeprecationWarning)
+    WorkingSet)
 
 
 # from Python 3.6 docs.
@@ -501,7 +501,6 @@ class TestEntryPoints:
             ep.load(require=False)
 
 
-
 class TestRequirements:
     def testBasics(self):
         r = Requirement.parse("Twisted>=1.2")
diff --git a/pyproject.toml b/pyproject.toml
index 07c23bb5..f0fd8521 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,5 +1,7 @@
 [build-system]
-requires = ["wheel"]
+requires = ["setuptools >= 40.8", "wheel"]
+build-backend = "setuptools.build_meta"
+backend-path = ["."]
 
 [tool.towncrier]
     package = "setuptools"
diff --git a/pytest.ini b/pytest.ini
index 0bc1ec01..904fe336 100644
--- a/pytest.ini
+++ b/pytest.ini
@@ -1,9 +1,6 @@
 [pytest]
-addopts=--doctest-modules --doctest-glob=pkg_resources/api_tests.txt -r sxX
-norecursedirs=dist build *.egg setuptools/extern pkg_resources/extern pkg_resources/tests/data tools .*
-flake8-ignore =
-    setuptools/site-patch.py F821
-    setuptools/py*compat.py F811
+addopts=--doctest-modules --flake8 --doctest-glob=pkg_resources/api_tests.txt -r sxX
+norecursedirs=dist build *.egg setuptools/extern pkg_resources/extern pkg_resources/tests/data tools .* setuptools/_vendor pkg_resources/_vendor
 doctest_optionflags=ELLIPSIS ALLOW_UNICODE
 filterwarnings =
 	# https://github.com/pypa/setuptools/issues/1823
diff --git a/setup.cfg b/setup.cfg
index 42a3d86c..bef019ee 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -14,12 +14,9 @@ repository = https://upload.pypi.org/legacy/
 [sdist]
 formats = zip
 
-[bdist_wheel]
-universal = 1
-
 [metadata]
 name = setuptools
-version = 41.6.0
+version = 45.1.0
 description = Easily download, build, install, upgrade, and uninstall Python packages
 author = Python Packaging Authority
 author_email = distutils-sig@python.org
@@ -35,10 +32,8 @@ classifiers =
     Intended Audience :: Developers
     License :: OSI Approved :: MIT License
     Operating System :: OS Independent
-    Programming Language :: Python :: 2
-    Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.4
+    Programming Language :: Python :: 3 :: Only
     Programming Language :: Python :: 3.5
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
@@ -50,7 +45,7 @@ classifiers =
 
 [options]
 zip_safe = True
-python_requires = >=2.7,!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*
+python_requires = >=3.5
 py_modules = easy_install
 packages = find:
 
diff --git a/setup.py b/setup.py
index d97895fc..277b6640 100755
--- a/setup.py
+++ b/setup.py
@@ -89,6 +89,13 @@ setup_params = dict(
             "%(cmd)s = setuptools.command.%(cmd)s:%(cmd)s" % locals()
             for cmd in read_commands()
         ],
+        "setuptools.finalize_distribution_options": [
+            "parent_finalize = setuptools.dist:_Distribution.finalize_options",
+            "features = setuptools.dist:Distribution._finalize_feature_opts",
+            "keywords = setuptools.dist:Distribution._finalize_setup_keywords",
+            "2to3_doctests = "
+            "setuptools.dist:Distribution._finalize_2to3_doctests",
+        ],
         "distutils.setup_keywords": [
             "eager_resources        = setuptools.dist:assert_string_list",
             "namespace_packages     = setuptools.dist:check_nsp",
diff --git a/setuptools/__init__.py b/setuptools/__init__.py
index a71b2bbd..07d6b6fa 100644
--- a/setuptools/__init__.py
+++ b/setuptools/__init__.py
@@ -1,7 +1,6 @@
 """Extensions to the 'distutils' for large or complex distributions"""
 
 import os
-import sys
 import functools
 import distutils.core
 import distutils.filelist
@@ -31,7 +30,7 @@ __all__ = [
 ]
 
 if PY3:
-  __all__.append('find_namespace_packages')
+    __all__.append('find_namespace_packages')
 
 __version__ = setuptools.version.__version__
 
@@ -123,7 +122,7 @@ class PEP420PackageFinder(PackageFinder):
 find_packages = PackageFinder.find
 
 if PY3:
-  find_namespace_packages = PEP420PackageFinder.find
+    find_namespace_packages = PEP420PackageFinder.find
 
 
 def _install_setup_requires(attrs):
@@ -144,6 +143,7 @@ def setup(**attrs):
     _install_setup_requires(attrs)
     return distutils.core.setup(**attrs)
 
+
 setup.__doc__ = distutils.core.setup.__doc__
 
 
@@ -191,8 +191,8 @@ class Command(_Command):
                 ok = False
             if not ok:
                 raise DistutilsOptionError(
-                      "'%s' must be a list of strings (got %r)"
-                      % (option, val))
+                    "'%s' must be a list of strings (got %r)"
+                    % (option, val))
 
     def reinitialize_command(self, command, reinit_subcommands=0, **kw):
         cmd = _Command.reinitialize_command(self, command, reinit_subcommands)
diff --git a/setuptools/_vendor/packaging/__about__.py b/setuptools/_vendor/packaging/__about__.py
index 95d330ef..dc95138d 100644
--- a/setuptools/_vendor/packaging/__about__.py
+++ b/setuptools/_vendor/packaging/__about__.py
@@ -4,18 +4,24 @@
 from __future__ import absolute_import, division, print_function
 
 __all__ = [
-    "__title__", "__summary__", "__uri__", "__version__", "__author__",
-    "__email__", "__license__", "__copyright__",
+    "__title__",
+    "__summary__",
+    "__uri__",
+    "__version__",
+    "__author__",
+    "__email__",
+    "__license__",
+    "__copyright__",
 ]
 
 __title__ = "packaging"
 __summary__ = "Core utilities for Python packages"
 __uri__ = "https://github.com/pypa/packaging"
 
-__version__ = "16.8"
+__version__ = "19.2"
 
 __author__ = "Donald Stufft and individual contributors"
 __email__ = "donald@stufft.io"
 
 __license__ = "BSD or Apache License, Version 2.0"
-__copyright__ = "Copyright 2014-2016 %s" % __author__
+__copyright__ = "Copyright 2014-2019 %s" % __author__
diff --git a/setuptools/_vendor/packaging/__init__.py b/setuptools/_vendor/packaging/__init__.py
index 5ee62202..a0cf67df 100644
--- a/setuptools/_vendor/packaging/__init__.py
+++ b/setuptools/_vendor/packaging/__init__.py
@@ -4,11 +4,23 @@
 from __future__ import absolute_import, division, print_function
 
 from .__about__ import (
-    __author__, __copyright__, __email__, __license__, __summary__, __title__,
-    __uri__, __version__
+    __author__,
+    __copyright__,
+    __email__,
+    __license__,
+    __summary__,
+    __title__,
+    __uri__,
+    __version__,
 )
 
 __all__ = [
-    "__title__", "__summary__", "__uri__", "__version__", "__author__",
-    "__email__", "__license__", "__copyright__",
+    "__title__",
+    "__summary__",
+    "__uri__",
+    "__version__",
+    "__author__",
+    "__email__",
+    "__license__",
+    "__copyright__",
 ]
diff --git a/setuptools/_vendor/packaging/_compat.py b/setuptools/_vendor/packaging/_compat.py
index 210bb80b..25da473c 100644
--- a/setuptools/_vendor/packaging/_compat.py
+++ b/setuptools/_vendor/packaging/_compat.py
@@ -12,9 +12,9 @@ PY3 = sys.version_info[0] == 3
 # flake8: noqa
 
 if PY3:
-    string_types = str,
+    string_types = (str,)
 else:
-    string_types = basestring,
+    string_types = (basestring,)
 
 
 def with_metaclass(meta, *bases):
@@ -27,4 +27,5 @@ def with_metaclass(meta, *bases):
     class metaclass(meta):
         def __new__(cls, name, this_bases, d):
             return meta(name, bases, d)
-    return type.__new__(metaclass, 'temporary_class', (), {})
+
+    return type.__new__(metaclass, "temporary_class", (), {})
diff --git a/setuptools/_vendor/packaging/_structures.py b/setuptools/_vendor/packaging/_structures.py
index ccc27861..68dcca63 100644
--- a/setuptools/_vendor/packaging/_structures.py
+++ b/setuptools/_vendor/packaging/_structures.py
@@ -5,7 +5,6 @@ from __future__ import absolute_import, division, print_function
 
 
 class Infinity(object):
-
     def __repr__(self):
         return "Infinity"
 
@@ -33,11 +32,11 @@ class Infinity(object):
     def __neg__(self):
         return NegativeInfinity
 
+
 Infinity = Infinity()
 
 
 class NegativeInfinity(object):
-
     def __repr__(self):
         return "-Infinity"
 
@@ -65,4 +64,5 @@ class NegativeInfinity(object):
     def __neg__(self):
         return Infinity
 
+
 NegativeInfinity = NegativeInfinity()
diff --git a/setuptools/_vendor/packaging/markers.py b/setuptools/_vendor/packaging/markers.py
index 031332a3..4bdfdb24 100644
--- a/setuptools/_vendor/packaging/markers.py
+++ b/setuptools/_vendor/packaging/markers.py
@@ -17,8 +17,11 @@ from .specifiers import Specifier, InvalidSpecifier
 
 
 __all__ = [
-    "InvalidMarker", "UndefinedComparison", "UndefinedEnvironmentName",
-    "Marker", "default_environment",
+    "InvalidMarker",
+    "UndefinedComparison",
+    "UndefinedEnvironmentName",
+    "Marker",
+    "default_environment",
 ]
 
 
@@ -42,7 +45,6 @@ class UndefinedEnvironmentName(ValueError):
 
 
 class Node(object):
-
     def __init__(self, value):
         self.value = value
 
@@ -57,62 +59,52 @@ class Node(object):
 
 
 class Variable(Node):
-
     def serialize(self):
         return str(self)
 
 
 class Value(Node):
-
     def serialize(self):
         return '"{0}"'.format(self)
 
 
 class Op(Node):
-
     def serialize(self):
         return str(self)
 
 
 VARIABLE = (
-    L("implementation_version") |
-    L("platform_python_implementation") |
-    L("implementation_name") |
-    L("python_full_version") |
-    L("platform_release") |
-    L("platform_version") |
-    L("platform_machine") |
-    L("platform_system") |
-    L("python_version") |
-    L("sys_platform") |
-    L("os_name") |
-    L("os.name") |  # PEP-345
-    L("sys.platform") |  # PEP-345
-    L("platform.version") |  # PEP-345
-    L("platform.machine") |  # PEP-345
-    L("platform.python_implementation") |  # PEP-345
-    L("python_implementation") |  # undocumented setuptools legacy
-    L("extra")
+    L("implementation_version")
+    | L("platform_python_implementation")
+    | L("implementation_name")
+    | L("python_full_version")
+    | L("platform_release")
+    | L("platform_version")
+    | L("platform_machine")
+    | L("platform_system")
+    | L("python_version")
+    | L("sys_platform")
+    | L("os_name")
+    | L("os.name")
+    | L("sys.platform")  # PEP-345
+    | L("platform.version")  # PEP-345
+    | L("platform.machine")  # PEP-345
+    | L("platform.python_implementation")  # PEP-345
+    | L("python_implementation")  # PEP-345
+    | L("extra")  # undocumented setuptools legacy
 )
 ALIASES = {
-    'os.name': 'os_name',
-    'sys.platform': 'sys_platform',
-    'platform.version': 'platform_version',
-    'platform.machine': 'platform_machine',
-    'platform.python_implementation': 'platform_python_implementation',
-    'python_implementation': 'platform_python_implementation'
+    "os.name": "os_name",
+    "sys.platform": "sys_platform",
+    "platform.version": "platform_version",
+    "platform.machine": "platform_machine",
+    "platform.python_implementation": "platform_python_implementation",
+    "python_implementation": "platform_python_implementation",
 }
 VARIABLE.setParseAction(lambda s, l, t: Variable(ALIASES.get(t[0], t[0])))
 
 VERSION_CMP = (
-    L("===") |
-    L("==") |
-    L(">=") |
-    L("<=") |
-    L("!=") |
-    L("~=") |
-    L(">") |
-    L("<")
+    L("===") | L("==") | L(">=") | L("<=") | L("!=") | L("~=") | L(">") | L("<")
 )
 
 MARKER_OP = VERSION_CMP | L("not in") | L("in")
@@ -152,8 +144,11 @@ def _format_marker(marker, first=True):
     # where the single item is itself it's own list. In that case we want skip
     # the rest of this function so that we don't get extraneous () on the
     # outside.
-    if (isinstance(marker, list) and len(marker) == 1 and
-            isinstance(marker[0], (list, tuple))):
+    if (
+        isinstance(marker, list)
+        and len(marker) == 1
+        and isinstance(marker[0], (list, tuple))
+    ):
         return _format_marker(marker[0])
 
     if isinstance(marker, list):
@@ -239,20 +234,20 @@ def _evaluate_markers(markers, environment):
 
 
 def format_full_version(info):
-    version = '{0.major}.{0.minor}.{0.micro}'.format(info)
+    version = "{0.major}.{0.minor}.{0.micro}".format(info)
     kind = info.releaselevel
-    if kind != 'final':
+    if kind != "final":
         version += kind[0] + str(info.serial)
     return version
 
 
 def default_environment():
-    if hasattr(sys, 'implementation'):
+    if hasattr(sys, "implementation"):
         iver = format_full_version(sys.implementation.version)
         implementation_name = sys.implementation.name
     else:
-        iver = '0'
-        implementation_name = ''
+        iver = "0"
+        implementation_name = ""
 
     return {
         "implementation_name": implementation_name,
@@ -264,19 +259,19 @@ def default_environment():
         "platform_version": platform.version(),
         "python_full_version": platform.python_version(),
         "platform_python_implementation": platform.python_implementation(),
-        "python_version": platform.python_version()[:3],
+        "python_version": ".".join(platform.python_version_tuple()[:2]),
         "sys_platform": sys.platform,
     }
 
 
 class Marker(object):
-
     def __init__(self, marker):
         try:
             self._markers = _coerce_parse_result(MARKER.parseString(marker))
         except ParseException as e:
             err_str = "Invalid marker: {0!r}, parse error at {1!r}".format(
-                marker, marker[e.loc:e.loc + 8])
+                marker, marker[e.loc : e.loc + 8]
+            )
             raise InvalidMarker(err_str)
 
     def __str__(self):
diff --git a/setuptools/_vendor/packaging/requirements.py b/setuptools/_vendor/packaging/requirements.py
index 5b493416..8a0c2cb9 100644
--- a/setuptools/_vendor/packaging/requirements.py
+++ b/setuptools/_vendor/packaging/requirements.py
@@ -38,8 +38,8 @@ IDENTIFIER = Combine(ALPHANUM + ZeroOrMore(IDENTIFIER_END))
 NAME = IDENTIFIER("name")
 EXTRA = IDENTIFIER
 
-URI = Regex(r'[^ ]+')("url")
-URL = (AT + URI)
+URI = Regex(r"[^ ]+")("url")
+URL = AT + URI
 
 EXTRAS_LIST = EXTRA + ZeroOrMore(COMMA + EXTRA)
 EXTRAS = (LBRACKET + Optional(EXTRAS_LIST) + RBRACKET)("extras")
@@ -48,28 +48,31 @@ VERSION_PEP440 = Regex(Specifier._regex_str, re.VERBOSE | re.IGNORECASE)
 VERSION_LEGACY = Regex(LegacySpecifier._regex_str, re.VERBOSE | re.IGNORECASE)
 
 VERSION_ONE = VERSION_PEP440 ^ VERSION_LEGACY
-VERSION_MANY = Combine(VERSION_ONE + ZeroOrMore(COMMA + VERSION_ONE),
-                       joinString=",", adjacent=False)("_raw_spec")
+VERSION_MANY = Combine(
+    VERSION_ONE + ZeroOrMore(COMMA + VERSION_ONE), joinString=",", adjacent=False
+)("_raw_spec")
 _VERSION_SPEC = Optional(((LPAREN + VERSION_MANY + RPAREN) | VERSION_MANY))
-_VERSION_SPEC.setParseAction(lambda s, l, t: t._raw_spec or '')
+_VERSION_SPEC.setParseAction(lambda s, l, t: t._raw_spec or "")
 
 VERSION_SPEC = originalTextFor(_VERSION_SPEC)("specifier")
 VERSION_SPEC.setParseAction(lambda s, l, t: t[1])
 
 MARKER_EXPR = originalTextFor(MARKER_EXPR())("marker")
 MARKER_EXPR.setParseAction(
-    lambda s, l, t: Marker(s[t._original_start:t._original_end])
+    lambda s, l, t: Marker(s[t._original_start : t._original_end])
 )
-MARKER_SEPERATOR = SEMICOLON
-MARKER = MARKER_SEPERATOR + MARKER_EXPR
+MARKER_SEPARATOR = SEMICOLON
+MARKER = MARKER_SEPARATOR + MARKER_EXPR
 
 VERSION_AND_MARKER = VERSION_SPEC + Optional(MARKER)
 URL_AND_MARKER = URL + Optional(MARKER)
 
-NAMED_REQUIREMENT = \
-    NAME + Optional(EXTRAS) + (URL_AND_MARKER | VERSION_AND_MARKER)
+NAMED_REQUIREMENT = NAME + Optional(EXTRAS) + (URL_AND_MARKER | VERSION_AND_MARKER)
 
 REQUIREMENT = stringStart + NAMED_REQUIREMENT + stringEnd
+# setuptools.extern.pyparsing isn't thread safe during initialization, so we do it eagerly, see
+# issue #104
+REQUIREMENT.parseString("x[]")
 
 
 class Requirement(object):
@@ -90,15 +93,21 @@ class Requirement(object):
             req = REQUIREMENT.parseString(requirement_string)
         except ParseException as e:
             raise InvalidRequirement(
-                "Invalid requirement, parse error at \"{0!r}\"".format(
-                    requirement_string[e.loc:e.loc + 8]))
+                'Parse error at "{0!r}": {1}'.format(
+                    requirement_string[e.loc : e.loc + 8], e.msg
+                )
+            )
 
         self.name = req.name
         if req.url:
             parsed_url = urlparse.urlparse(req.url)
-            if not (parsed_url.scheme and parsed_url.netloc) or (
-                    not parsed_url.scheme and not parsed_url.netloc):
-                raise InvalidRequirement("Invalid URL given")
+            if parsed_url.scheme == "file":
+                if urlparse.urlunparse(parsed_url) != req.url:
+                    raise InvalidRequirement("Invalid URL given")
+            elif not (parsed_url.scheme and parsed_url.netloc) or (
+                not parsed_url.scheme and not parsed_url.netloc
+            ):
+                raise InvalidRequirement("Invalid URL: {0}".format(req.url))
             self.url = req.url
         else:
             self.url = None
@@ -117,6 +126,8 @@ class Requirement(object):
 
         if self.url:
             parts.append("@ {0}".format(self.url))
+            if self.marker:
+                parts.append(" ")
 
         if self.marker:
             parts.append("; {0}".format(self.marker))
diff --git a/setuptools/_vendor/packaging/specifiers.py b/setuptools/_vendor/packaging/specifiers.py
index 7f5a76cf..743576a0 100644
--- a/setuptools/_vendor/packaging/specifiers.py
+++ b/setuptools/_vendor/packaging/specifiers.py
@@ -19,7 +19,6 @@ class InvalidSpecifier(ValueError):
 
 
 class BaseSpecifier(with_metaclass(abc.ABCMeta, object)):
-
     @abc.abstractmethod
     def __str__(self):
         """
@@ -84,10 +83,7 @@ class _IndividualSpecifier(BaseSpecifier):
         if not match:
             raise InvalidSpecifier("Invalid specifier: '{0}'".format(spec))
 
-        self._spec = (
-            match.group("operator").strip(),
-            match.group("version").strip(),
-        )
+        self._spec = (match.group("operator").strip(), match.group("version").strip())
 
         # Store whether or not this Specifier should accept prereleases
         self._prereleases = prereleases
@@ -99,11 +95,7 @@ class _IndividualSpecifier(BaseSpecifier):
             else ""
         )
 
-        return "<{0}({1!r}{2})>".format(
-            self.__class__.__name__,
-            str(self),
-            pre,
-        )
+        return "<{0}({1!r}{2})>".format(self.__class__.__name__, str(self), pre)
 
     def __str__(self):
         return "{0}{1}".format(*self._spec)
@@ -194,11 +186,12 @@ class _IndividualSpecifier(BaseSpecifier):
                 # If our version is a prerelease, and we were not set to allow
                 # prereleases, then we'll store it for later incase nothing
                 # else matches this specifier.
-                if (parsed_version.is_prerelease and not
-                        (prereleases or self.prereleases)):
+                if parsed_version.is_prerelease and not (
+                    prereleases or self.prereleases
+                ):
                     found_prereleases.append(version)
                 # Either this is not a prerelease, or we should have been
-                # accepting prereleases from the begining.
+                # accepting prereleases from the beginning.
                 else:
                     yielded = True
                     yield version
@@ -213,8 +206,7 @@ class _IndividualSpecifier(BaseSpecifier):
 
 class LegacySpecifier(_IndividualSpecifier):
 
-    _regex_str = (
-        r"""
+    _regex_str = r"""
         (?P<operator>(==|!=|<=|>=|<|>))
         \s*
         (?P<version>
@@ -225,10 +217,8 @@ class LegacySpecifier(_IndividualSpecifier):
                       # them, and a comma since it's a version separator.
         )
         """
-    )
 
-    _regex = re.compile(
-        r"^\s*" + _regex_str + r"\s*$", re.VERBOSE | re.IGNORECASE)
+    _regex = re.compile(r"^\s*" + _regex_str + r"\s*$", re.VERBOSE | re.IGNORECASE)
 
     _operators = {
         "==": "equal",
@@ -269,13 +259,13 @@ def _require_version_compare(fn):
         if not isinstance(prospective, Version):
             return False
         return fn(self, prospective, spec)
+
     return wrapped
 
 
 class Specifier(_IndividualSpecifier):
 
-    _regex_str = (
-        r"""
+    _regex_str = r"""
         (?P<operator>(~=|==|!=|<=|>=|<|>|===))
         (?P<version>
             (?:
@@ -367,10 +357,8 @@ class Specifier(_IndividualSpecifier):
             )
         )
         """
-    )
 
-    _regex = re.compile(
-        r"^\s*" + _regex_str + r"\s*$", re.VERBOSE | re.IGNORECASE)
+    _regex = re.compile(r"^\s*" + _regex_str + r"\s*$", re.VERBOSE | re.IGNORECASE)
 
     _operators = {
         "~=": "compatible",
@@ -397,8 +385,7 @@ class Specifier(_IndividualSpecifier):
         prefix = ".".join(
             list(
                 itertools.takewhile(
-                    lambda x: (not x.startswith("post") and not
-                               x.startswith("dev")),
+                    lambda x: (not x.startswith("post") and not x.startswith("dev")),
                     _version_split(spec),
                 )
             )[:-1]
@@ -407,8 +394,9 @@ class Specifier(_IndividualSpecifier):
         # Add the prefix notation to the end of our string
         prefix += ".*"
 
-        return (self._get_operator(">=")(prospective, spec) and
-                self._get_operator("==")(prospective, prefix))
+        return self._get_operator(">=")(prospective, spec) and self._get_operator("==")(
+            prospective, prefix
+        )
 
     @_require_version_compare
     def _compare_equal(self, prospective, spec):
@@ -428,7 +416,7 @@ class Specifier(_IndividualSpecifier):
             # Shorten the prospective version to be the same length as the spec
             # so that we can determine if the specifier is a prefix of the
             # prospective version or not.
-            prospective = prospective[:len(spec)]
+            prospective = prospective[: len(spec)]
 
             # Pad out our two sides with zeros so that they both equal the same
             # length.
@@ -503,7 +491,7 @@ class Specifier(_IndividualSpecifier):
                 return False
 
         # Ensure that we do not allow a local version of the version mentioned
-        # in the specifier, which is techincally greater than, to match.
+        # in the specifier, which is technically greater than, to match.
         if prospective.local is not None:
             if Version(prospective.base_version) == Version(spec.base_version):
                 return False
@@ -567,27 +555,17 @@ def _pad_version(left, right):
     right_split.append(list(itertools.takewhile(lambda x: x.isdigit(), right)))
 
     # Get the rest of our versions
-    left_split.append(left[len(left_split[0]):])
-    right_split.append(right[len(right_split[0]):])
+    left_split.append(left[len(left_split[0]) :])
+    right_split.append(right[len(right_split[0]) :])
 
     # Insert our padding
-    left_split.insert(
-        1,
-        ["0"] * max(0, len(right_split[0]) - len(left_split[0])),
-    )
-    right_split.insert(
-        1,
-        ["0"] * max(0, len(left_split[0]) - len(right_split[0])),
-    )
+    left_split.insert(1, ["0"] * max(0, len(right_split[0]) - len(left_split[0])))
+    right_split.insert(1, ["0"] * max(0, len(left_split[0]) - len(right_split[0])))
 
-    return (
-        list(itertools.chain(*left_split)),
-        list(itertools.chain(*right_split)),
-    )
+    return (list(itertools.chain(*left_split)), list(itertools.chain(*right_split)))
 
 
 class SpecifierSet(BaseSpecifier):
-
     def __init__(self, specifiers="", prereleases=None):
         # Split on , to break each indidivual specifier into it's own item, and
         # strip each item to remove leading/trailing whitespace.
@@ -721,10 +699,7 @@ class SpecifierSet(BaseSpecifier):
         # given version is contained within all of them.
         # Note: This use of all() here means that an empty set of specifiers
         #       will always return True, this is an explicit design decision.
-        return all(
-            s.contains(item, prereleases=prereleases)
-            for s in self._specs
-        )
+        return all(s.contains(item, prereleases=prereleases) for s in self._specs)
 
     def filter(self, iterable, prereleases=None):
         # Determine if we're forcing a prerelease or not, if we're not forcing
diff --git a/setuptools/_vendor/packaging/tags.py b/setuptools/_vendor/packaging/tags.py
new file mode 100644
index 00000000..ec9942f0
--- /dev/null
+++ b/setuptools/_vendor/packaging/tags.py
@@ -0,0 +1,404 @@
+# This file is dual licensed under the terms of the Apache License, Version
+# 2.0, and the BSD License. See the LICENSE file in the root of this repository
+# for complete details.
+
+from __future__ import absolute_import
+
+import distutils.util
+
+try:
+    from importlib.machinery import EXTENSION_SUFFIXES
+except ImportError:  # pragma: no cover
+    import imp
+
+    EXTENSION_SUFFIXES = [x[0] for x in imp.get_suffixes()]
+    del imp
+import platform
+import re
+import sys
+import sysconfig
+import warnings
+
+
+INTERPRETER_SHORT_NAMES = {
+    "python": "py",  # Generic.
+    "cpython": "cp",
+    "pypy": "pp",
+    "ironpython": "ip",
+    "jython": "jy",
+}
+
+
+_32_BIT_INTERPRETER = sys.maxsize <= 2 ** 32
+
+
+class Tag(object):
+
+    __slots__ = ["_interpreter", "_abi", "_platform"]
+
+    def __init__(self, interpreter, abi, platform):
+        self._interpreter = interpreter.lower()
+        self._abi = abi.lower()
+        self._platform = platform.lower()
+
+    @property
+    def interpreter(self):
+        return self._interpreter
+
+    @property
+    def abi(self):
+        return self._abi
+
+    @property
+    def platform(self):
+        return self._platform
+
+    def __eq__(self, other):
+        return (
+            (self.platform == other.platform)
+            and (self.abi == other.abi)
+            and (self.interpreter == other.interpreter)
+        )
+
+    def __hash__(self):
+        return hash((self._interpreter, self._abi, self._platform))
+
+    def __str__(self):
+        return "{}-{}-{}".format(self._interpreter, self._abi, self._platform)
+
+    def __repr__(self):
+        return "<{self} @ {self_id}>".format(self=self, self_id=id(self))
+
+
+def parse_tag(tag):
+    tags = set()
+    interpreters, abis, platforms = tag.split("-")
+    for interpreter in interpreters.split("."):
+        for abi in abis.split("."):
+            for platform_ in platforms.split("."):
+                tags.add(Tag(interpreter, abi, platform_))
+    return frozenset(tags)
+
+
+def _normalize_string(string):
+    return string.replace(".", "_").replace("-", "_")
+
+
+def _cpython_interpreter(py_version):
+    # TODO: Is using py_version_nodot for interpreter version critical?
+    return "cp{major}{minor}".format(major=py_version[0], minor=py_version[1])
+
+
+def _cpython_abis(py_version):
+    abis = []
+    version = "{}{}".format(*py_version[:2])
+    debug = pymalloc = ucs4 = ""
+    with_debug = sysconfig.get_config_var("Py_DEBUG")
+    has_refcount = hasattr(sys, "gettotalrefcount")
+    # Windows doesn't set Py_DEBUG, so checking for support of debug-compiled
+    # extension modules is the best option.
+    # https://github.com/pypa/pip/issues/3383#issuecomment-173267692
+    has_ext = "_d.pyd" in EXTENSION_SUFFIXES
+    if with_debug or (with_debug is None and (has_refcount or has_ext)):
+        debug = "d"
+    if py_version < (3, 8):
+        with_pymalloc = sysconfig.get_config_var("WITH_PYMALLOC")
+        if with_pymalloc or with_pymalloc is None:
+            pymalloc = "m"
+        if py_version < (3, 3):
+            unicode_size = sysconfig.get_config_var("Py_UNICODE_SIZE")
+            if unicode_size == 4 or (
+                unicode_size is None and sys.maxunicode == 0x10FFFF
+            ):
+                ucs4 = "u"
+    elif debug:
+        # Debug builds can also load "normal" extension modules.
+        # We can also assume no UCS-4 or pymalloc requirement.
+        abis.append("cp{version}".format(version=version))
+    abis.insert(
+        0,
+        "cp{version}{debug}{pymalloc}{ucs4}".format(
+            version=version, debug=debug, pymalloc=pymalloc, ucs4=ucs4
+        ),
+    )
+    return abis
+
+
+def _cpython_tags(py_version, interpreter, abis, platforms):
+    for abi in abis:
+        for platform_ in platforms:
+            yield Tag(interpreter, abi, platform_)
+    for tag in (Tag(interpreter, "abi3", platform_) for platform_ in platforms):
+        yield tag
+    for tag in (Tag(interpreter, "none", platform_) for platform_ in platforms):
+        yield tag
+    # PEP 384 was first implemented in Python 3.2.
+    for minor_version in range(py_version[1] - 1, 1, -1):
+        for platform_ in platforms:
+            interpreter = "cp{major}{minor}".format(
+                major=py_version[0], minor=minor_version
+            )
+            yield Tag(interpreter, "abi3", platform_)
+
+
+def _pypy_interpreter():
+    return "pp{py_major}{pypy_major}{pypy_minor}".format(
+        py_major=sys.version_info[0],
+        pypy_major=sys.pypy_version_info.major,
+        pypy_minor=sys.pypy_version_info.minor,
+    )
+
+
+def _generic_abi():
+    abi = sysconfig.get_config_var("SOABI")
+    if abi:
+        return _normalize_string(abi)
+    else:
+        return "none"
+
+
+def _pypy_tags(py_version, interpreter, abi, platforms):
+    for tag in (Tag(interpreter, abi, platform) for platform in platforms):
+        yield tag
+    for tag in (Tag(interpreter, "none", platform) for platform in platforms):
+        yield tag
+
+
+def _generic_tags(interpreter, py_version, abi, platforms):
+    for tag in (Tag(interpreter, abi, platform) for platform in platforms):
+        yield tag
+    if abi != "none":
+        tags = (Tag(interpreter, "none", platform_) for platform_ in platforms)
+        for tag in tags:
+            yield tag
+
+
+def _py_interpreter_range(py_version):
+    """
+    Yield Python versions in descending order.
+
+    After the latest version, the major-only version will be yielded, and then
+    all following versions up to 'end'.
+    """
+    yield "py{major}{minor}".format(major=py_version[0], minor=py_version[1])
+    yield "py{major}".format(major=py_version[0])
+    for minor in range(py_version[1] - 1, -1, -1):
+        yield "py{major}{minor}".format(major=py_version[0], minor=minor)
+
+
+def _independent_tags(interpreter, py_version, platforms):
+    """
+    Return the sequence of tags that are consistent across implementations.
+
+    The tags consist of:
+    - py*-none-<platform>
+    - <interpreter>-none-any
+    - py*-none-any
+    """
+    for version in _py_interpreter_range(py_version):
+        for platform_ in platforms:
+            yield Tag(version, "none", platform_)
+    yield Tag(interpreter, "none", "any")
+    for version in _py_interpreter_range(py_version):
+        yield Tag(version, "none", "any")
+
+
+def _mac_arch(arch, is_32bit=_32_BIT_INTERPRETER):
+    if not is_32bit:
+        return arch
+
+    if arch.startswith("ppc"):
+        return "ppc"
+
+    return "i386"
+
+
+def _mac_binary_formats(version, cpu_arch):
+    formats = [cpu_arch]
+    if cpu_arch == "x86_64":
+        if version < (10, 4):
+            return []
+        formats.extend(["intel", "fat64", "fat32"])
+
+    elif cpu_arch == "i386":
+        if version < (10, 4):
+            return []
+        formats.extend(["intel", "fat32", "fat"])
+
+    elif cpu_arch == "ppc64":
+        # TODO: Need to care about 32-bit PPC for ppc64 through 10.2?
+        if version > (10, 5) or version < (10, 4):
+            return []
+        formats.append("fat64")
+
+    elif cpu_arch == "ppc":
+        if version > (10, 6):
+            return []
+        formats.extend(["fat32", "fat"])
+
+    formats.append("universal")
+    return formats
+
+
+def _mac_platforms(version=None, arch=None):
+    version_str, _, cpu_arch = platform.mac_ver()
+    if version is None:
+        version = tuple(map(int, version_str.split(".")[:2]))
+    if arch is None:
+        arch = _mac_arch(cpu_arch)
+    platforms = []
+    for minor_version in range(version[1], -1, -1):
+        compat_version = version[0], minor_version
+        binary_formats = _mac_binary_formats(compat_version, arch)
+        for binary_format in binary_formats:
+            platforms.append(
+                "macosx_{major}_{minor}_{binary_format}".format(
+                    major=compat_version[0],
+                    minor=compat_version[1],
+                    binary_format=binary_format,
+                )
+            )
+    return platforms
+
+
+# From PEP 513.
+def _is_manylinux_compatible(name, glibc_version):
+    # Check for presence of _manylinux module.
+    try:
+        import _manylinux
+
+        return bool(getattr(_manylinux, name + "_compatible"))
+    except (ImportError, AttributeError):
+        # Fall through to heuristic check below.
+        pass
+
+    return _have_compatible_glibc(*glibc_version)
+
+
+def _glibc_version_string():
+    # Returns glibc version string, or None if not using glibc.
+    import ctypes
+
+    # ctypes.CDLL(None) internally calls dlopen(NULL), and as the dlopen
+    # manpage says, "If filename is NULL, then the returned handle is for the
+    # main program". This way we can let the linker do the work to figure out
+    # which libc our process is actually using.
+    process_namespace = ctypes.CDLL(None)
+    try:
+        gnu_get_libc_version = process_namespace.gnu_get_libc_version
+    except AttributeError:
+        # Symbol doesn't exist -> therefore, we are not linked to
+        # glibc.
+        return None
+
+    # Call gnu_get_libc_version, which returns a string like "2.5"
+    gnu_get_libc_version.restype = ctypes.c_char_p
+    version_str = gnu_get_libc_version()
+    # py2 / py3 compatibility:
+    if not isinstance(version_str, str):
+        version_str = version_str.decode("ascii")
+
+    return version_str
+
+
+# Separated out from have_compatible_glibc for easier unit testing.
+def _check_glibc_version(version_str, required_major, minimum_minor):
+    # Parse string and check against requested version.
+    #
+    # We use a regexp instead of str.split because we want to discard any
+    # random junk that might come after the minor version -- this might happen
+    # in patched/forked versions of glibc (e.g. Linaro's version of glibc
+    # uses version strings like "2.20-2014.11"). See gh-3588.
+    m = re.match(r"(?P<major>[0-9]+)\.(?P<minor>[0-9]+)", version_str)
+    if not m:
+        warnings.warn(
+            "Expected glibc version with 2 components major.minor,"
+            " got: %s" % version_str,
+            RuntimeWarning,
+        )
+        return False
+    return (
+        int(m.group("major")) == required_major
+        and int(m.group("minor")) >= minimum_minor
+    )
+
+
+def _have_compatible_glibc(required_major, minimum_minor):
+    version_str = _glibc_version_string()
+    if version_str is None:
+        return False
+    return _check_glibc_version(version_str, required_major, minimum_minor)
+
+
+def _linux_platforms(is_32bit=_32_BIT_INTERPRETER):
+    linux = _normalize_string(distutils.util.get_platform())
+    if linux == "linux_x86_64" and is_32bit:
+        linux = "linux_i686"
+    manylinux_support = (
+        ("manylinux2014", (2, 17)),  # CentOS 7 w/ glibc 2.17 (PEP 599)
+        ("manylinux2010", (2, 12)),  # CentOS 6 w/ glibc 2.12 (PEP 571)
+        ("manylinux1", (2, 5)),  # CentOS 5 w/ glibc 2.5 (PEP 513)
+    )
+    manylinux_support_iter = iter(manylinux_support)
+    for name, glibc_version in manylinux_support_iter:
+        if _is_manylinux_compatible(name, glibc_version):
+            platforms = [linux.replace("linux", name)]
+            break
+    else:
+        platforms = []
+    # Support for a later manylinux implies support for an earlier version.
+    platforms += [linux.replace("linux", name) for name, _ in manylinux_support_iter]
+    platforms.append(linux)
+    return platforms
+
+
+def _generic_platforms():
+    platform = _normalize_string(distutils.util.get_platform())
+    return [platform]
+
+
+def _interpreter_name():
+    name = platform.python_implementation().lower()
+    return INTERPRETER_SHORT_NAMES.get(name) or name
+
+
+def _generic_interpreter(name, py_version):
+    version = sysconfig.get_config_var("py_version_nodot")
+    if not version:
+        version = "".join(map(str, py_version[:2]))
+    return "{name}{version}".format(name=name, version=version)
+
+
+def sys_tags():
+    """
+    Returns the sequence of tag triples for the running interpreter.
+
+    The order of the sequence corresponds to priority order for the
+    interpreter, from most to least important.
+    """
+    py_version = sys.version_info[:2]
+    interpreter_name = _interpreter_name()
+    if platform.system() == "Darwin":
+        platforms = _mac_platforms()
+    elif platform.system() == "Linux":
+        platforms = _linux_platforms()
+    else:
+        platforms = _generic_platforms()
+
+    if interpreter_name == "cp":
+        interpreter = _cpython_interpreter(py_version)
+        abis = _cpython_abis(py_version)
+        for tag in _cpython_tags(py_version, interpreter, abis, platforms):
+            yield tag
+    elif interpreter_name == "pp":
+        interpreter = _pypy_interpreter()
+        abi = _generic_abi()
+        for tag in _pypy_tags(py_version, interpreter, abi, platforms):
+            yield tag
+    else:
+        interpreter = _generic_interpreter(interpreter_name, py_version)
+        abi = _generic_abi()
+        for tag in _generic_tags(interpreter, py_version, abi, platforms):
+            yield tag
+    for tag in _independent_tags(interpreter, py_version, platforms):
+        yield tag
diff --git a/setuptools/_vendor/packaging/utils.py b/setuptools/_vendor/packaging/utils.py
index 942387ce..88418786 100644
--- a/setuptools/_vendor/packaging/utils.py
+++ b/setuptools/_vendor/packaging/utils.py
@@ -5,6 +5,8 @@ from __future__ import absolute_import, division, print_function
 
 import re
 
+from .version import InvalidVersion, Version
+
 
 _canonicalize_regex = re.compile(r"[-_.]+")
 
@@ -12,3 +14,44 @@ _canonicalize_regex = re.compile(r"[-_.]+")
 def canonicalize_name(name):
     # This is taken from PEP 503.
     return _canonicalize_regex.sub("-", name).lower()
+
+
+def canonicalize_version(version):
+    """
+    This is very similar to Version.__str__, but has one subtle differences
+    with the way it handles the release segment.
+    """
+
+    try:
+        version = Version(version)
+    except InvalidVersion:
+        # Legacy versions cannot be normalized
+        return version
+
+    parts = []
+
+    # Epoch
+    if version.epoch != 0:
+        parts.append("{0}!".format(version.epoch))
+
+    # Release segment
+    # NB: This strips trailing '.0's to normalize
+    parts.append(re.sub(r"(\.0)+$", "", ".".join(str(x) for x in version.release)))
+
+    # Pre-release
+    if version.pre is not None:
+        parts.append("".join(str(x) for x in version.pre))
+
+    # Post-release
+    if version.post is not None:
+        parts.append(".post{0}".format(version.post))
+
+    # Development release
+    if version.dev is not None:
+        parts.append(".dev{0}".format(version.dev))
+
+    # Local version segment
+    if version.local is not None:
+        parts.append("+{0}".format(version.local))
+
+    return "".join(parts)
diff --git a/setuptools/_vendor/packaging/version.py b/setuptools/_vendor/packaging/version.py
index 83b5ee8c..95157a1f 100644
--- a/setuptools/_vendor/packaging/version.py
+++ b/setuptools/_vendor/packaging/version.py
@@ -10,14 +10,11 @@ import re
 from ._structures import Infinity
 
 
-__all__ = [
-    "parse", "Version", "LegacyVersion", "InvalidVersion", "VERSION_PATTERN"
-]
+__all__ = ["parse", "Version", "LegacyVersion", "InvalidVersion", "VERSION_PATTERN"]
 
 
 _Version = collections.namedtuple(
-    "_Version",
-    ["epoch", "release", "dev", "pre", "post", "local"],
+    "_Version", ["epoch", "release", "dev", "pre", "post", "local"]
 )
 
 
@@ -40,7 +37,6 @@ class InvalidVersion(ValueError):
 
 
 class _BaseVersion(object):
-
     def __hash__(self):
         return hash(self._key)
 
@@ -70,7 +66,6 @@ class _BaseVersion(object):
 
 
 class LegacyVersion(_BaseVersion):
-
     def __init__(self, version):
         self._version = str(version)
         self._key = _legacy_cmpkey(self._version)
@@ -90,6 +85,26 @@ class LegacyVersion(_BaseVersion):
         return self._version
 
     @property
+    def epoch(self):
+        return -1
+
+    @property
+    def release(self):
+        return None
+
+    @property
+    def pre(self):
+        return None
+
+    @property
+    def post(self):
+        return None
+
+    @property
+    def dev(self):
+        return None
+
+    @property
     def local(self):
         return None
 
@@ -101,13 +116,19 @@ class LegacyVersion(_BaseVersion):
     def is_postrelease(self):
         return False
 
+    @property
+    def is_devrelease(self):
+        return False
 
-_legacy_version_component_re = re.compile(
-    r"(\d+ | [a-z]+ | \.| -)", re.VERBOSE,
-)
+
+_legacy_version_component_re = re.compile(r"(\d+ | [a-z]+ | \.| -)", re.VERBOSE)
 
 _legacy_version_replacement_map = {
-    "pre": "c", "preview": "c", "-": "final-", "rc": "c", "dev": "@",
+    "pre": "c",
+    "preview": "c",
+    "-": "final-",
+    "rc": "c",
+    "dev": "@",
 }
 
 
@@ -154,6 +175,7 @@ def _legacy_cmpkey(version):
 
     return epoch, parts
 
+
 # Deliberately not anchored to the start and end of the string, to make it
 # easier for 3rd party code to reuse
 VERSION_PATTERN = r"""
@@ -190,10 +212,7 @@ VERSION_PATTERN = r"""
 
 class Version(_BaseVersion):
 
-    _regex = re.compile(
-        r"^\s*" + VERSION_PATTERN + r"\s*$",
-        re.VERBOSE | re.IGNORECASE,
-    )
+    _regex = re.compile(r"^\s*" + VERSION_PATTERN + r"\s*$", re.VERBOSE | re.IGNORECASE)
 
     def __init__(self, version):
         # Validate the version and parse it into pieces
@@ -205,18 +224,11 @@ class Version(_BaseVersion):
         self._version = _Version(
             epoch=int(match.group("epoch")) if match.group("epoch") else 0,
             release=tuple(int(i) for i in match.group("release").split(".")),
-            pre=_parse_letter_version(
-                match.group("pre_l"),
-                match.group("pre_n"),
-            ),
+            pre=_parse_letter_version(match.group("pre_l"), match.group("pre_n")),
             post=_parse_letter_version(
-                match.group("post_l"),
-                match.group("post_n1") or match.group("post_n2"),
-            ),
-            dev=_parse_letter_version(
-                match.group("dev_l"),
-                match.group("dev_n"),
+                match.group("post_l"), match.group("post_n1") or match.group("post_n2")
             ),
+            dev=_parse_letter_version(match.group("dev_l"), match.group("dev_n")),
             local=_parse_local_version(match.group("local")),
         )
 
@@ -237,33 +249,58 @@ class Version(_BaseVersion):
         parts = []
 
         # Epoch
-        if self._version.epoch != 0:
-            parts.append("{0}!".format(self._version.epoch))
+        if self.epoch != 0:
+            parts.append("{0}!".format(self.epoch))
 
         # Release segment
-        parts.append(".".join(str(x) for x in self._version.release))
+        parts.append(".".join(str(x) for x in self.release))
 
         # Pre-release
-        if self._version.pre is not None:
-            parts.append("".join(str(x) for x in self._version.pre))
+        if self.pre is not None:
+            parts.append("".join(str(x) for x in self.pre))
 
         # Post-release
-        if self._version.post is not None:
-            parts.append(".post{0}".format(self._version.post[1]))
+        if self.post is not None:
+            parts.append(".post{0}".format(self.post))
 
         # Development release
-        if self._version.dev is not None:
-            parts.append(".dev{0}".format(self._version.dev[1]))
+        if self.dev is not None:
+            parts.append(".dev{0}".format(self.dev))
 
         # Local version segment
-        if self._version.local is not None:
-            parts.append(
-                "+{0}".format(".".join(str(x) for x in self._version.local))
-            )
+        if self.local is not None:
+            parts.append("+{0}".format(self.local))
 
         return "".join(parts)
 
     @property
+    def epoch(self):
+        return self._version.epoch
+
+    @property
+    def release(self):
+        return self._version.release
+
+    @property
+    def pre(self):
+        return self._version.pre
+
+    @property
+    def post(self):
+        return self._version.post[1] if self._version.post else None
+
+    @property
+    def dev(self):
+        return self._version.dev[1] if self._version.dev else None
+
+    @property
+    def local(self):
+        if self._version.local:
+            return ".".join(str(x) for x in self._version.local)
+        else:
+            return None
+
+    @property
     def public(self):
         return str(self).split("+", 1)[0]
 
@@ -272,27 +309,25 @@ class Version(_BaseVersion):
         parts = []
 
         # Epoch
-        if self._version.epoch != 0:
-            parts.append("{0}!".format(self._version.epoch))
+        if self.epoch != 0:
+            parts.append("{0}!".format(self.epoch))
 
         # Release segment
-        parts.append(".".join(str(x) for x in self._version.release))
+        parts.append(".".join(str(x) for x in self.release))
 
         return "".join(parts)
 
     @property
-    def local(self):
-        version_string = str(self)
-        if "+" in version_string:
-            return version_string.split("+", 1)[1]
-
-    @property
     def is_prerelease(self):
-        return bool(self._version.dev or self._version.pre)
+        return self.dev is not None or self.pre is not None
 
     @property
     def is_postrelease(self):
-        return bool(self._version.post)
+        return self.post is not None
+
+    @property
+    def is_devrelease(self):
+        return self.dev is not None
 
 
 def _parse_letter_version(letter, number):
@@ -326,7 +361,7 @@ def _parse_letter_version(letter, number):
         return letter, int(number)
 
 
-_local_version_seperators = re.compile(r"[\._-]")
+_local_version_separators = re.compile(r"[\._-]")
 
 
 def _parse_local_version(local):
@@ -336,7 +371,7 @@ def _parse_local_version(local):
     if local is not None:
         return tuple(
             part.lower() if not part.isdigit() else int(part)
-            for part in _local_version_seperators.split(local)
+            for part in _local_version_separators.split(local)
         )
 
 
@@ -347,12 +382,7 @@ def _cmpkey(epoch, release, pre, post, dev, local):
     # re-reverse it back into the correct order and make it a tuple and use
     # that for our sorting key.
     release = tuple(
-        reversed(list(
-            itertools.dropwhile(
-                lambda x: x == 0,
-                reversed(release),
-            )
-        ))
+        reversed(list(itertools.dropwhile(lambda x: x == 0, reversed(release))))
     )
 
     # We need to "trick" the sorting algorithm to put 1.0.dev0 before 1.0a0.
@@ -385,9 +415,6 @@ def _cmpkey(epoch, release, pre, post, dev, local):
         # - Numeric segments sort numerically
         # - Shorter versions sort before longer versions when the prefixes
         #   match exactly
-        local = tuple(
-            (i, "") if isinstance(i, int) else (-Infinity, i)
-            for i in local
-        )
+        local = tuple((i, "") if isinstance(i, int) else (-Infinity, i) for i in local)
 
     return epoch, release, pre, post, dev, local
diff --git a/setuptools/_vendor/vendored.txt b/setuptools/_vendor/vendored.txt
index 5731b424..65183d9a 100644
--- a/setuptools/_vendor/vendored.txt
+++ b/setuptools/_vendor/vendored.txt
@@ -1,4 +1,4 @@
-packaging==16.8
+packaging==19.2
 pyparsing==2.2.1
 six==1.10.0
 ordered-set==3.1.1
diff --git a/setuptools/archive_util.py b/setuptools/archive_util.py
index 81436044..64528ca7 100644
--- a/setuptools/archive_util.py
+++ b/setuptools/archive_util.py
@@ -25,7 +25,8 @@ def default_filter(src, dst):
     return dst
 
 
-def unpack_archive(filename, extract_dir, progress_filter=default_filter,
+def unpack_archive(
+        filename, extract_dir, progress_filter=default_filter,
         drivers=None):
     """Unpack `filename` to `extract_dir`, or raise ``UnrecognizedFormat``
 
@@ -148,7 +149,8 @@ def unpack_tarfile(filename, extract_dir, progress_filter=default_filter):
 
                 # resolve any links and to extract the link targets as normal
                 # files
-                while member is not None and (member.islnk() or member.issym()):
+                while member is not None and (
+                        member.islnk() or member.issym()):
                     linkpath = member.linkname
                     if member.issym():
                         base = posixpath.dirname(member.name)
diff --git a/setuptools/build_meta.py b/setuptools/build_meta.py
index 10c4b528..a1c951cf 100644
--- a/setuptools/build_meta.py
+++ b/setuptools/build_meta.py
@@ -48,6 +48,7 @@ __all__ = ['get_requires_for_build_sdist',
            '__legacy__',
            'SetupRequirementsError']
 
+
 class SetupRequirementsError(BaseException):
     def __init__(self, specifiers):
         self.specifiers = specifiers
@@ -143,7 +144,8 @@ class _BuildMetaBackend(object):
 
     def get_requires_for_build_wheel(self, config_settings=None):
         config_settings = self._fix_config(config_settings)
-        return self._get_build_requires(config_settings, requirements=['wheel'])
+        return self._get_build_requires(
+            config_settings, requirements=['wheel'])
 
     def get_requires_for_build_sdist(self, config_settings=None):
         config_settings = self._fix_config(config_settings)
@@ -160,8 +162,10 @@ class _BuildMetaBackend(object):
             dist_infos = [f for f in os.listdir(dist_info_directory)
                           if f.endswith('.dist-info')]
 
-            if (len(dist_infos) == 0 and
-                len(_get_immediate_subdirectories(dist_info_directory)) == 1):
+            if (
+                len(dist_infos) == 0 and
+                len(_get_immediate_subdirectories(dist_info_directory)) == 1
+            ):
 
                 dist_info_directory = os.path.join(
                     dist_info_directory, os.listdir(dist_info_directory)[0])
@@ -193,7 +197,8 @@ class _BuildMetaBackend(object):
                         config_settings["--global-option"])
             self.run_setup()
 
-            result_basename = _file_with_extension(tmp_dist_dir, result_extension)
+            result_basename = _file_with_extension(
+                tmp_dist_dir, result_extension)
             result_path = os.path.join(result_directory, result_basename)
             if os.path.exists(result_path):
                 # os.rename will fail overwriting on non-Unix.
@@ -202,7 +207,6 @@ class _BuildMetaBackend(object):
 
         return result_basename
 
-
     def build_wheel(self, wheel_directory, config_settings=None,
                     metadata_directory=None):
         return self._build_with_temp_dir(['bdist_wheel'], '.whl',
@@ -217,9 +221,12 @@ class _BuildMetaBackend(object):
 class _BuildMetaLegacyBackend(_BuildMetaBackend):
     """Compatibility backend for setuptools
 
-    This is a version of setuptools.build_meta that endeavors to maintain backwards
-    compatibility with pre-PEP 517 modes of invocation. It exists as a temporary
-    bridge between the old packaging mechanism and the new packaging mechanism,
+    This is a version of setuptools.build_meta that endeavors
+    to maintain backwards
+    compatibility with pre-PEP 517 modes of invocation. It
+    exists as a temporary
+    bridge between the old packaging mechanism and the new
+    packaging mechanism,
     and will eventually be removed.
     """
     def run_setup(self, setup_script='setup.py'):
@@ -232,6 +239,12 @@ class _BuildMetaLegacyBackend(_BuildMetaBackend):
         if script_dir not in sys.path:
             sys.path.insert(0, script_dir)
 
+        # Some setup.py scripts (e.g. in pygame and numpy) use sys.argv[0] to
+        # get the directory of the source code. They expect it to refer to the
+        # setup.py script.
+        sys_argv_0 = sys.argv[0]
+        sys.argv[0] = setup_script
+
         try:
             super(_BuildMetaLegacyBackend,
                   self).run_setup(setup_script=setup_script)
@@ -242,6 +255,8 @@ class _BuildMetaLegacyBackend(_BuildMetaBackend):
             # the original path so that the path manipulation does not persist
             # within the hook after run_setup is called.
             sys.path[:] = sys_path
+            sys.argv[0] = sys_argv_0
+
 
 # The primary backend
 _BACKEND = _BuildMetaBackend()
diff --git a/setuptools/command/build_clib.py b/setuptools/command/build_clib.py
index 09caff6f..67ce2444 100644
--- a/setuptools/command/build_clib.py
+++ b/setuptools/command/build_clib.py
@@ -25,9 +25,9 @@ class build_clib(orig.build_clib):
             sources = build_info.get('sources')
             if sources is None or not isinstance(sources, (list, tuple)):
                 raise DistutilsSetupError(
-                       "in 'libraries' option (library '%s'), "
-                       "'sources' must be present and must be "
-                       "a list of source filenames" % lib_name)
+                    "in 'libraries' option (library '%s'), "
+                    "'sources' must be present and must be "
+                    "a list of source filenames" % lib_name)
             sources = list(sources)
 
             log.info("building '%s' library", lib_name)
@@ -38,9 +38,9 @@ class build_clib(orig.build_clib):
             obj_deps = build_info.get('obj_deps', dict())
             if not isinstance(obj_deps, dict):
                 raise DistutilsSetupError(
-                       "in 'libraries' option (library '%s'), "
-                       "'obj_deps' must be a dictionary of "
-                       "type 'source: list'" % lib_name)
+                    "in 'libraries' option (library '%s'), "
+                    "'obj_deps' must be a dictionary of "
+                    "type 'source: list'" % lib_name)
             dependencies = []
 
             # Get the global dependencies that are specified by the '' key.
@@ -48,9 +48,9 @@ class build_clib(orig.build_clib):
             global_deps = obj_deps.get('', list())
             if not isinstance(global_deps, (list, tuple)):
                 raise DistutilsSetupError(
-                       "in 'libraries' option (library '%s'), "
-                       "'obj_deps' must be a dictionary of "
-                       "type 'source: list'" % lib_name)
+                    "in 'libraries' option (library '%s'), "
+                    "'obj_deps' must be a dictionary of "
+                    "type 'source: list'" % lib_name)
 
             # Build the list to be used by newer_pairwise_group
             # each source will be auto-added to its dependencies.
@@ -60,39 +60,42 @@ class build_clib(orig.build_clib):
                 extra_deps = obj_deps.get(source, list())
                 if not isinstance(extra_deps, (list, tuple)):
                     raise DistutilsSetupError(
-                           "in 'libraries' option (library '%s'), "
-                           "'obj_deps' must be a dictionary of "
-                           "type 'source: list'" % lib_name)
+                        "in 'libraries' option (library '%s'), "
+                        "'obj_deps' must be a dictionary of "
+                        "type 'source: list'" % lib_name)
                 src_deps.extend(extra_deps)
                 dependencies.append(src_deps)
 
             expected_objects = self.compiler.object_filenames(
-                    sources,
-                    output_dir=self.build_temp
-                    )
+                sources,
+                output_dir=self.build_temp,
+            )
 
-            if newer_pairwise_group(dependencies, expected_objects) != ([], []):
+            if (
+                newer_pairwise_group(dependencies, expected_objects)
+                != ([], [])
+            ):
                 # First, compile the source code to object files in the library
                 # directory.  (This should probably change to putting object
                 # files in a temporary build directory.)
                 macros = build_info.get('macros')
                 include_dirs = build_info.get('include_dirs')
                 cflags = build_info.get('cflags')
-                objects = self.compiler.compile(
-                        sources,
-                        output_dir=self.build_temp,
-                        macros=macros,
-                        include_dirs=include_dirs,
-                        extra_postargs=cflags,
-                        debug=self.debug
-                        )
+                self.compiler.compile(
+                    sources,
+                    output_dir=self.build_temp,
+                    macros=macros,
+                    include_dirs=include_dirs,
+                    extra_postargs=cflags,
+                    debug=self.debug
+                )
 
             # Now "link" the object files together into a static library.
             # (On Unix at least, this isn't really linking -- it just
             # builds an archive.  Whatever.)
             self.compiler.create_static_lib(
-                    expected_objects,
-                    lib_name,
-                    output_dir=self.build_clib,
-                    debug=self.debug
-                    )
+                expected_objects,
+                lib_name,
+                output_dir=self.build_clib,
+                debug=self.debug
+            )
diff --git a/setuptools/command/build_ext.py b/setuptools/command/build_ext.py
index daa8e4fe..03b6f346 100644
--- a/setuptools/command/build_ext.py
+++ b/setuptools/command/build_ext.py
@@ -14,7 +14,8 @@ from setuptools.extern import six
 if six.PY2:
     import imp
 
-    EXTENSION_SUFFIXES = [s for s, _, tp in imp.get_suffixes() if tp == imp.C_EXTENSION]
+    EXTENSION_SUFFIXES = [
+        s for s, _, tp in imp.get_suffixes() if tp == imp.C_EXTENSION]
 else:
     from importlib.machinery import EXTENSION_SUFFIXES
 
@@ -29,7 +30,7 @@ except ImportError:
 
 # make sure _config_vars is initialized
 get_config_var("LDSHARED")
-from distutils.sysconfig import _config_vars as _CONFIG_VARS
+from distutils.sysconfig import _config_vars as _CONFIG_VARS  # noqa
 
 
 def _customize_compiler_for_shlib(compiler):
@@ -65,7 +66,9 @@ elif os.name != 'nt':
     except ImportError:
         pass
 
-if_dl = lambda s: s if have_rtld else ''
+
+def if_dl(s):
+    return s if have_rtld else ''
 
 
 def get_abi3_suffix():
@@ -113,7 +116,7 @@ class build_ext(_build_ext):
         if fullname in self.ext_map:
             ext = self.ext_map[fullname]
             use_abi3 = (
-                six.PY3
+                not six.PY2
                 and getattr(ext, 'py_limited_api')
                 and get_abi3_suffix()
             )
diff --git a/setuptools/command/develop.py b/setuptools/command/develop.py
index 009e4f93..b5619246 100644
--- a/setuptools/command/develop.py
+++ b/setuptools/command/develop.py
@@ -108,7 +108,7 @@ class develop(namespaces.DevelopInstaller, easy_install):
         return path_to_setup
 
     def install_for_development(self):
-        if six.PY3 and getattr(self.distribution, 'use_2to3', False):
+        if not six.PY2 and getattr(self.distribution, 'use_2to3', False):
             # If we run 2to3 we can not do this inplace:
 
             # Ensure metadata is up-to-date
diff --git a/setuptools/command/easy_install.py b/setuptools/command/easy_install.py
index 545c3c44..b95ef1f6 100644
--- a/setuptools/command/easy_install.py
+++ b/setuptools/command/easy_install.py
@@ -121,7 +121,8 @@ else:
             return False
 
 
-_one_liner = lambda text: textwrap.dedent(text).strip().replace('\n', '; ')
+def _one_liner(text):
+    return textwrap.dedent(text).strip().replace('\n', '; ')
 
 
 class easy_install(Command):
@@ -410,7 +411,13 @@ class easy_install(Command):
         ]
         self._expand_attrs(dirs)
 
-    def run(self):
+    def run(self, show_deprecation=True):
+        if show_deprecation:
+            self.announce(
+                "WARNING: The easy_install command is deprecated "
+                "and will be removed in a future version.",
+                log.WARN,
+            )
         if self.verbose != self.distribution.verbose:
             log.set_verbosity(self.verbose)
         try:
@@ -501,13 +508,13 @@ class easy_install(Command):
         the distutils default setting) was:
 
             %s
-        """).lstrip()
+        """).lstrip()  # noqa
 
     __not_exists_id = textwrap.dedent("""
         This directory does not currently exist.  Please create it and try again, or
         choose a different installation directory (using the -d or --install-dir
         option).
-        """).lstrip()
+        """).lstrip()  # noqa
 
     __access_msg = textwrap.dedent("""
         Perhaps your account does not have write access to this directory?  If the
@@ -523,7 +530,7 @@ class easy_install(Command):
           https://setuptools.readthedocs.io/en/latest/easy_install.html
 
         Please make the appropriate changes for your system and try again.
-        """).lstrip()
+        """).lstrip()  # noqa
 
     def cant_write_to_target(self):
         msg = self.__cant_write_msg % (sys.exc_info()[1], self.install_dir,)
@@ -1087,13 +1094,13 @@ class easy_install(Command):
             pkg_resources.require("%(name)s")  # latest installed version
             pkg_resources.require("%(name)s==%(version)s")  # this exact version
             pkg_resources.require("%(name)s>=%(version)s")  # this version or higher
-        """).lstrip()
+        """).lstrip()  # noqa
 
     __id_warning = textwrap.dedent("""
         Note also that the installation directory must be on sys.path at runtime for
         this to work.  (e.g. by being the application's script directory, by being on
         PYTHONPATH, or by being added to sys.path by your code.)
-        """)
+        """)  # noqa
 
     def installation_report(self, req, dist, what="Installed"):
         """Helpful installation message for display to package users"""
@@ -1118,7 +1125,7 @@ class easy_install(Command):
             %(python)s setup.py develop
 
         See the setuptools documentation for the "develop" command for more info.
-        """).lstrip()
+        """).lstrip()  # noqa
 
     def report_editable(self, spec, setup_script):
         dirname = os.path.dirname(setup_script)
@@ -1301,7 +1308,8 @@ class easy_install(Command):
           https://setuptools.readthedocs.io/en/latest/easy_install.html#custom-installation-locations
 
 
-        Please make the appropriate changes for your system and try again.""").lstrip()
+        Please make the appropriate changes for your system and try again.
+        """).strip()
 
     def no_default_version_msg(self):
         template = self.__no_default_msg
@@ -1561,7 +1569,7 @@ def get_exe_prefixes(exe_filename):
                 continue
             if parts[0].upper() in ('PURELIB', 'PLATLIB'):
                 contents = z.read(name)
-                if six.PY3:
+                if not six.PY2:
                     contents = contents.decode()
                 for pth in yield_lines(contents):
                     pth = pth.strip().replace('\\', '/')
@@ -2087,7 +2095,8 @@ class ScriptWriter:
     @classmethod
     def get_script_header(cls, script_text, executable=None, wininst=False):
         # for backward compatibility
-        warnings.warn("Use get_header", EasyInstallDeprecationWarning, stacklevel=2)
+        warnings.warn(
+            "Use get_header", EasyInstallDeprecationWarning, stacklevel=2)
         if wininst:
             executable = "python.exe"
         return cls.get_header(script_text, executable)
@@ -2336,6 +2345,8 @@ def _patch_usage():
     finally:
         distutils.core.gen_usage = saved
 
+
 class EasyInstallDeprecationWarning(SetuptoolsDeprecationWarning):
-    """Class for warning about deprecations in EasyInstall in SetupTools. Not ignored by default, unlike DeprecationWarning."""
-    
+    """
+    Warning for EasyInstall deprecations, bypassing suppression.
+    """
diff --git a/setuptools/command/egg_info.py b/setuptools/command/egg_info.py
index 5d8f451e..7fa89541 100644
--- a/setuptools/command/egg_info.py
+++ b/setuptools/command/egg_info.py
@@ -33,6 +33,7 @@ from setuptools.glob import glob
 from setuptools.extern import packaging
 from setuptools import SetuptoolsDeprecationWarning
 
+
 def translate_pattern(glob):
     """
     Translate a file path glob like '*.txt' in to a regular expression.
@@ -113,7 +114,7 @@ def translate_pattern(glob):
             pat += sep
 
     pat += r'\Z'
-    return re.compile(pat, flags=re.MULTILINE|re.DOTALL)
+    return re.compile(pat, flags=re.MULTILINE | re.DOTALL)
 
 
 class InfoCommon:
@@ -266,7 +267,7 @@ class egg_info(InfoCommon, Command):
         to the file.
         """
         log.info("writing %s to %s", what, filename)
-        if six.PY3:
+        if not six.PY2:
             data = data.encode("utf-8")
         if not self.dry_run:
             f = open(filename, 'wb')
@@ -637,7 +638,9 @@ def warn_depends_obsolete(cmd, basename, filename):
 
 def _write_requirements(stream, reqs):
     lines = yield_lines(reqs or ())
-    append_cr = lambda line: line + '\n'
+
+    def append_cr(line):
+        return line + '\n'
     lines = map(append_cr, lines)
     stream.writelines(lines)
 
@@ -703,7 +706,8 @@ def get_pkg_info_revision():
     Get a -r### off of PKG-INFO Version in case this is an sdist of
     a subversion revision.
     """
-    warnings.warn("get_pkg_info_revision is deprecated.", EggInfoDeprecationWarning)
+    warnings.warn(
+        "get_pkg_info_revision is deprecated.", EggInfoDeprecationWarning)
     if os.path.exists('PKG-INFO'):
         with io.open('PKG-INFO') as f:
             for line in f:
@@ -714,4 +718,4 @@ def get_pkg_info_revision():
 
 
 class EggInfoDeprecationWarning(SetuptoolsDeprecationWarning):
-    """Class for warning about deprecations in eggInfo in setupTools. Not ignored by default, unlike DeprecationWarning."""
+    """Deprecated behavior warning for EggInfo, bypassing suppression."""
diff --git a/setuptools/command/install.py b/setuptools/command/install.py
index 31a5ddb5..72b9a3e4 100644
--- a/setuptools/command/install.py
+++ b/setuptools/command/install.py
@@ -114,7 +114,7 @@ class install(orig.install):
             args.insert(0, setuptools.bootstrap_install_from)
 
         cmd.args = args
-        cmd.run()
+        cmd.run(show_deprecation=False)
         setuptools.bootstrap_install_from = None
 
 
diff --git a/setuptools/command/install_lib.py b/setuptools/command/install_lib.py
index 07d65933..2e9d8757 100644
--- a/setuptools/command/install_lib.py
+++ b/setuptools/command/install_lib.py
@@ -77,7 +77,8 @@ class install_lib(orig.install_lib):
         if not hasattr(sys, 'implementation'):
             return
 
-        base = os.path.join('__pycache__', '__init__.' + sys.implementation.cache_tag)
+        base = os.path.join(
+            '__pycache__', '__init__.' + sys.implementation.cache_tag)
         yield base + '.pyc'
         yield base + '.pyo'
         yield base + '.opt-1.pyc'
diff --git a/setuptools/command/py36compat.py b/setuptools/command/py36compat.py
index 61063e75..28860558 100644
--- a/setuptools/command/py36compat.py
+++ b/setuptools/command/py36compat.py
@@ -132,5 +132,5 @@ class sdist_add_defaults:
 
 if hasattr(sdist.sdist, '_add_defaults_standards'):
     # disable the functionality already available upstream
-    class sdist_add_defaults:
+    class sdist_add_defaults:  # noqa
         pass
diff --git a/setuptools/command/sdist.py b/setuptools/command/sdist.py
index dc253981..8c3438ea 100644
--- a/setuptools/command/sdist.py
+++ b/setuptools/command/sdist.py
@@ -5,7 +5,7 @@ import sys
 import io
 import contextlib
 
-from setuptools.extern import six
+from setuptools.extern import six, ordered_set
 
 from .py36compat import sdist_add_defaults
 
@@ -121,19 +121,40 @@ class sdist(sdist_add_defaults, orig.sdist):
     if has_leaky_handle:
         read_template = __read_template_hack
 
+    def _add_defaults_optional(self):
+        if six.PY2:
+            sdist_add_defaults._add_defaults_optional(self)
+        else:
+            super()._add_defaults_optional()
+        if os.path.isfile('pyproject.toml'):
+            self.filelist.append('pyproject.toml')
+
     def _add_defaults_python(self):
         """getting python files"""
         if self.distribution.has_pure_modules():
             build_py = self.get_finalized_command('build_py')
             self.filelist.extend(build_py.get_source_files())
-            # This functionality is incompatible with include_package_data, and
-            # will in fact create an infinite recursion if include_package_data
-            # is True.  Use of include_package_data will imply that
-            # distutils-style automatic handling of package_data is disabled
-            if not self.distribution.include_package_data:
-                for _, src_dir, _, filenames in build_py.data_files:
-                    self.filelist.extend([os.path.join(src_dir, filename)
-                                          for filename in filenames])
+            self._add_data_files(self._safe_data_files(build_py))
+
+    def _safe_data_files(self, build_py):
+        """
+        Extracting data_files from build_py is known to cause
+        infinite recursion errors when `include_package_data`
+        is enabled, so suppress it in that case.
+        """
+        if self.distribution.include_package_data:
+            return ()
+        return build_py.data_files
+
+    def _add_data_files(self, data_files):
+        """
+        Add data files as found in build_py.data_files.
+        """
+        self.filelist.extend(
+            os.path.join(src_dir, name)
+            for _, src_dir, _, filenames in data_files
+            for name in filenames
+        )
 
     def _add_defaults_data_files(self):
         try:
@@ -186,7 +207,7 @@ class sdist(sdist_add_defaults, orig.sdist):
         manifest = open(self.manifest, 'rb')
         for line in manifest:
             # The manifest must contain UTF-8. See #303.
-            if six.PY3:
+            if not six.PY2:
                 try:
                     line = line.decode('UTF-8')
                 except UnicodeDecodeError:
@@ -200,10 +221,12 @@ class sdist(sdist_add_defaults, orig.sdist):
         manifest.close()
 
     def check_license(self):
-        """Checks if license_file' is configured and adds it to
-        'self.filelist' if the value contains a valid path.
+        """Checks if license_file' or 'license_files' is configured and adds any
+        valid paths to 'self.filelist'.
         """
 
+        files = ordered_set.OrderedSet()
+
         opts = self.distribution.get_option_dict('metadata')
 
         # ignore the source of the value
@@ -211,11 +234,19 @@ class sdist(sdist_add_defaults, orig.sdist):
 
         if license_file is None:
             log.debug("'license_file' option was not specified")
-            return
+        else:
+            files.add(license_file)
 
-        if not os.path.exists(license_file):
-            log.warn("warning: Failed to find the configured license file '%s'",
-                    license_file)
-            return
+        try:
+            files.update(self.distribution.metadata.license_files)
+        except TypeError:
+            log.warn("warning: 'license_files' option is malformed")
+
+        for f in files:
+            if not os.path.exists(f):
+                log.warn(
+                    "warning: Failed to find the configured license file '%s'",
+                    f)
+                files.remove(f)
 
-        self.filelist.append(license_file)
+        self.filelist.extend(files)
diff --git a/setuptools/command/test.py b/setuptools/command/test.py
index c148b38d..2d83967d 100644
--- a/setuptools/command/test.py
+++ b/setuptools/command/test.py
@@ -129,7 +129,8 @@ class test(Command):
 
     @contextlib.contextmanager
     def project_on_sys_path(self, include_dists=[]):
-        with_2to3 = six.PY3 and getattr(self.distribution, 'use_2to3', False)
+        with_2to3 = not six.PY2 and getattr(
+            self.distribution, 'use_2to3', False)
 
         if with_2to3:
             # If we run 2to3 we can not do this inplace:
@@ -240,7 +241,7 @@ class test(Command):
         # Purge modules under test from sys.modules. The test loader will
         # re-import them from the build location. Required when 2to3 is used
         # with namespace packages.
-        if six.PY3 and getattr(self.distribution, 'use_2to3', False):
+        if not six.PY2 and getattr(self.distribution, 'use_2to3', False):
             module = self.test_suite.split('.')[0]
             if module in _namespace_packages:
                 del_modules = []
diff --git a/setuptools/command/upload_docs.py b/setuptools/command/upload_docs.py
index 07aa564a..0351da77 100644
--- a/setuptools/command/upload_docs.py
+++ b/setuptools/command/upload_docs.py
@@ -24,7 +24,7 @@ from .upload import upload
 
 
 def _encode(s):
-    errors = 'surrogateescape' if six.PY3 else 'strict'
+    errors = 'strict' if six.PY2 else 'surrogateescape'
     return s.encode('utf-8', errors)
 
 
@@ -127,8 +127,8 @@ class upload_docs(upload):
         """
         Build up the MIME payload for the POST data
         """
-        boundary = b'--------------GHSKFJDLGDS7543FJKLFHRE75642756743254'
-        sep_boundary = b'\n--' + boundary
+        boundary = '--------------GHSKFJDLGDS7543FJKLFHRE75642756743254'
+        sep_boundary = b'\n--' + boundary.encode('ascii')
         end_boundary = sep_boundary + b'--'
         end_items = end_boundary, b"\n",
         builder = functools.partial(
@@ -138,7 +138,7 @@ class upload_docs(upload):
         part_groups = map(builder, data.items())
         parts = itertools.chain.from_iterable(part_groups)
         body_items = itertools.chain(parts, end_items)
-        content_type = 'multipart/form-data; boundary=%s' % boundary.decode('ascii')
+        content_type = 'multipart/form-data; boundary=%s' % boundary
         return b''.join(body_items), content_type
 
     def upload_file(self, filename):
@@ -153,7 +153,7 @@ class upload_docs(upload):
         # set up the authentication
         credentials = _encode(self.username + ':' + self.password)
         credentials = standard_b64encode(credentials)
-        if six.PY3:
+        if not six.PY2:
             credentials = credentials.decode('ascii')
         auth = "Basic " + credentials
 
diff --git a/setuptools/config.py b/setuptools/config.py
index 2d50e25e..9b9a0c45 100644
--- a/setuptools/config.py
+++ b/setuptools/config.py
@@ -483,6 +483,7 @@ class ConfigMetadataHandler(ConfigHandler):
             'obsoletes': parse_list,
             'classifiers': self._get_parser_compound(parse_file, parse_list),
             'license': exclude_files_parser('license'),
+            'license_files': parse_list,
             'description': parse_file,
             'long_description': parse_file,
             'version': self._parse_version,
diff --git a/setuptools/dep_util.py b/setuptools/dep_util.py
index 2931c13e..521eb716 100644
--- a/setuptools/dep_util.py
+++ b/setuptools/dep_util.py
@@ -1,5 +1,6 @@
 from distutils.dep_util import newer_group
 
+
 # yes, this is was almost entirely copy-pasted from
 # 'newer_pairwise()', this is just another convenience
 # function.
@@ -10,7 +11,8 @@ def newer_pairwise_group(sources_groups, targets):
     of 'newer_group()'.
     """
     if len(sources_groups) != len(targets):
-        raise ValueError("'sources_group' and 'targets' must be the same length")
+        raise ValueError(
+            "'sources_group' and 'targets' must be the same length")
 
     # build a pair of lists (sources_groups, targets) where source is newer
     n_sources = []
diff --git a/setuptools/dist.py b/setuptools/dist.py
index 2e5ad4bd..ad54839b 100644
--- a/setuptools/dist.py
+++ b/setuptools/dist.py
@@ -162,7 +162,7 @@ def write_pkg_file(self, file):
     if self.download_url:
         write_field('Download-URL', self.download_url)
     for project_url in self.project_urls.items():
-        write_field('Project-URL',  '%s, %s' % project_url)
+        write_field('Project-URL', '%s, %s' % project_url)
 
     long_desc = rfc822_escape(self.get_long_description())
     write_field('Description', long_desc)
@@ -409,6 +409,7 @@ class Distribution(_Distribution):
         'long_description_content_type': None,
         'project_urls': dict,
         'provides_extras': ordered_set.OrderedSet,
+        'license_files': ordered_set.OrderedSet,
     }
 
     _patched_dist = None
@@ -570,7 +571,7 @@ class Distribution(_Distribution):
         from setuptools.extern.six.moves.configparser import ConfigParser
 
         # Ignore install directory options if we have a venv
-        if six.PY3 and sys.prefix != sys.base_prefix:
+        if not six.PY2 and sys.prefix != sys.base_prefix:
             ignore_options = [
                 'install-base', 'install-platbase', 'install-lib',
                 'install-platlib', 'install-purelib', 'install-headers',
@@ -592,7 +593,7 @@ class Distribution(_Distribution):
             with io.open(filename, encoding='utf-8') as reader:
                 if DEBUG:
                     self.announce("  reading {filename}".format(**locals()))
-                (parser.read_file if six.PY3 else parser.readfp)(reader)
+                (parser.readfp if six.PY2 else parser.read_file)(reader)
             for section in parser.sections():
                 options = parser.options(section)
                 opt_dict = self.get_option_dict(section)
@@ -635,7 +636,7 @@ class Distribution(_Distribution):
 
         Ref #1653
         """
-        if six.PY3:
+        if not six.PY2:
             return val
         try:
             return val.encode()
@@ -724,15 +725,28 @@ class Distribution(_Distribution):
         return resolved_dists
 
     def finalize_options(self):
-        _Distribution.finalize_options(self)
-        if self.features:
-            self._set_global_opts_from_features()
+        """
+        Allow plugins to apply arbitrary operations to the
+        distribution. Each hook may optionally define a 'order'
+        to influence the order of execution. Smaller numbers
+        go first and the default is 0.
+        """
+        hook_key = 'setuptools.finalize_distribution_options'
+
+        def by_order(hook):
+            return getattr(hook, 'order', 0)
+        eps = pkg_resources.iter_entry_points(hook_key)
+        for ep in sorted(eps, key=by_order):
+            ep.load()(self)
 
+    def _finalize_setup_keywords(self):
         for ep in pkg_resources.iter_entry_points('distutils.setup_keywords'):
             value = getattr(self, ep.name, None)
             if value is not None:
                 ep.require(installer=self.fetch_build_egg)
                 ep.load()(self, ep.name, value)
+
+    def _finalize_2to3_doctests(self):
         if getattr(self, 'convert_2to3_doctests', None):
             # XXX may convert to set here when we can rely on set being builtin
             self.convert_2to3_doctests = [
@@ -759,36 +773,15 @@ class Distribution(_Distribution):
 
     def fetch_build_egg(self, req):
         """Fetch an egg needed for building"""
-        from setuptools.command.easy_install import easy_install
-        dist = self.__class__({'script_args': ['easy_install']})
-        opts = dist.get_option_dict('easy_install')
-        opts.clear()
-        opts.update(
-            (k, v)
-            for k, v in self.get_option_dict('easy_install').items()
-            if k in (
-                # don't use any other settings
-                'find_links', 'site_dirs', 'index_url',
-                'optimize', 'site_dirs', 'allow_hosts',
-            ))
-        if self.dependency_links:
-            links = self.dependency_links[:]
-            if 'find_links' in opts:
-                links = opts['find_links'][1] + links
-            opts['find_links'] = ('setup', links)
-        install_dir = self.get_egg_cache_dir()
-        cmd = easy_install(
-            dist, args=["x"], install_dir=install_dir,
-            exclude_scripts=True,
-            always_copy=False, build_directory=None, editable=False,
-            upgrade=False, multi_version=True, no_report=True, user=False
-        )
-        cmd.ensure_finalized()
-        return cmd.easy_install(req)
+        from setuptools.installer import fetch_build_egg
+        return fetch_build_egg(self, req)
 
-    def _set_global_opts_from_features(self):
+    def _finalize_feature_opts(self):
         """Add --with-X/--without-X options based on optional features"""
 
+        if not self.features:
+            return
+
         go = []
         no = self.negative_opt.copy()
 
diff --git a/setuptools/glibc.py b/setuptools/glibc.py
deleted file mode 100644
index a134591c..00000000
--- a/setuptools/glibc.py
+++ /dev/null
@@ -1,86 +0,0 @@
-# This file originally from pip:
-# https://github.com/pypa/pip/blob/8f4f15a5a95d7d5b511ceaee9ed261176c181970/src/pip/_internal/utils/glibc.py
-from __future__ import absolute_import
-
-import ctypes
-import re
-import warnings
-
-
-def glibc_version_string():
-    "Returns glibc version string, or None if not using glibc."
-
-    # ctypes.CDLL(None) internally calls dlopen(NULL), and as the dlopen
-    # manpage says, "If filename is NULL, then the returned handle is for the
-    # main program". This way we can let the linker do the work to figure out
-    # which libc our process is actually using.
-    process_namespace = ctypes.CDLL(None)
-    try:
-        gnu_get_libc_version = process_namespace.gnu_get_libc_version
-    except AttributeError:
-        # Symbol doesn't exist -> therefore, we are not linked to
-        # glibc.
-        return None
-
-    # Call gnu_get_libc_version, which returns a string like "2.5"
-    gnu_get_libc_version.restype = ctypes.c_char_p
-    version_str = gnu_get_libc_version()
-    # py2 / py3 compatibility:
-    if not isinstance(version_str, str):
-        version_str = version_str.decode("ascii")
-
-    return version_str
-
-
-# Separated out from have_compatible_glibc for easier unit testing
-def check_glibc_version(version_str, required_major, minimum_minor):
-    # Parse string and check against requested version.
-    #
-    # We use a regexp instead of str.split because we want to discard any
-    # random junk that might come after the minor version -- this might happen
-    # in patched/forked versions of glibc (e.g. Linaro's version of glibc
-    # uses version strings like "2.20-2014.11"). See gh-3588.
-    m = re.match(r"(?P<major>[0-9]+)\.(?P<minor>[0-9]+)", version_str)
-    if not m:
-        warnings.warn("Expected glibc version with 2 components major.minor,"
-                      " got: %s" % version_str, RuntimeWarning)
-        return False
-    return (int(m.group("major")) == required_major and
-            int(m.group("minor")) >= minimum_minor)
-
-
-def have_compatible_glibc(required_major, minimum_minor):
-    version_str = glibc_version_string()
-    if version_str is None:
-        return False
-    return check_glibc_version(version_str, required_major, minimum_minor)
-
-
-# platform.libc_ver regularly returns completely nonsensical glibc
-# versions. E.g. on my computer, platform says:
-#
-#   ~$ python2.7 -c 'import platform; print(platform.libc_ver())'
-#   ('glibc', '2.7')
-#   ~$ python3.5 -c 'import platform; print(platform.libc_ver())'
-#   ('glibc', '2.9')
-#
-# But the truth is:
-#
-#   ~$ ldd --version
-#   ldd (Debian GLIBC 2.22-11) 2.22
-#
-# This is unfortunate, because it means that the linehaul data on libc
-# versions that was generated by pip 8.1.2 and earlier is useless and
-# misleading. Solution: instead of using platform, use our code that actually
-# works.
-def libc_ver():
-    """Try to determine the glibc version
-
-    Returns a tuple of strings (lib, version) which default to empty strings
-    in case the lookup fails.
-    """
-    glibc_version = glibc_version_string()
-    if glibc_version is None:
-        return ("", "")
-    else:
-        return ("glibc", glibc_version)
diff --git a/setuptools/installer.py b/setuptools/installer.py
new file mode 100644
index 00000000..1f183bd9
--- /dev/null
+++ b/setuptools/installer.py
@@ -0,0 +1,150 @@
+import glob
+import os
+import subprocess
+import sys
+from distutils import log
+from distutils.errors import DistutilsError
+
+import pkg_resources
+from setuptools.command.easy_install import easy_install
+from setuptools.extern import six
+from setuptools.wheel import Wheel
+
+from .py31compat import TemporaryDirectory
+
+
+def _fixup_find_links(find_links):
+    """Ensure find-links option end-up being a list of strings."""
+    if isinstance(find_links, six.string_types):
+        return find_links.split()
+    assert isinstance(find_links, (tuple, list))
+    return find_links
+
+
+def _legacy_fetch_build_egg(dist, req):
+    """Fetch an egg needed for building.
+
+    Legacy path using EasyInstall.
+    """
+    tmp_dist = dist.__class__({'script_args': ['easy_install']})
+    opts = tmp_dist.get_option_dict('easy_install')
+    opts.clear()
+    opts.update(
+        (k, v)
+        for k, v in dist.get_option_dict('easy_install').items()
+        if k in (
+            # don't use any other settings
+            'find_links', 'site_dirs', 'index_url',
+            'optimize', 'site_dirs', 'allow_hosts',
+        ))
+    if dist.dependency_links:
+        links = dist.dependency_links[:]
+        if 'find_links' in opts:
+            links = _fixup_find_links(opts['find_links'][1]) + links
+        opts['find_links'] = ('setup', links)
+    install_dir = dist.get_egg_cache_dir()
+    cmd = easy_install(
+        tmp_dist, args=["x"], install_dir=install_dir,
+        exclude_scripts=True,
+        always_copy=False, build_directory=None, editable=False,
+        upgrade=False, multi_version=True, no_report=True, user=False
+    )
+    cmd.ensure_finalized()
+    return cmd.easy_install(req)
+
+
+def fetch_build_egg(dist, req):
+    """Fetch an egg needed for building.
+
+    Use pip/wheel to fetch/build a wheel."""
+    # Check pip is available.
+    try:
+        pkg_resources.get_distribution('pip')
+    except pkg_resources.DistributionNotFound:
+        dist.announce(
+            'WARNING: The pip package is not available, falling back '
+            'to EasyInstall for handling setup_requires/test_requires; '
+            'this is deprecated and will be removed in a future version.',
+            log.WARN
+        )
+        return _legacy_fetch_build_egg(dist, req)
+    # Warn if wheel is not.
+    try:
+        pkg_resources.get_distribution('wheel')
+    except pkg_resources.DistributionNotFound:
+        dist.announce('WARNING: The wheel package is not available.', log.WARN)
+    # Ignore environment markers; if supplied, it is required.
+    req = strip_marker(req)
+    # Take easy_install options into account, but do not override relevant
+    # pip environment variables (like PIP_INDEX_URL or PIP_QUIET); they'll
+    # take precedence.
+    opts = dist.get_option_dict('easy_install')
+    if 'allow_hosts' in opts:
+        raise DistutilsError('the `allow-hosts` option is not supported '
+                             'when using pip to install requirements.')
+    if 'PIP_QUIET' in os.environ or 'PIP_VERBOSE' in os.environ:
+        quiet = False
+    else:
+        quiet = True
+    if 'PIP_INDEX_URL' in os.environ:
+        index_url = None
+    elif 'index_url' in opts:
+        index_url = opts['index_url'][1]
+    else:
+        index_url = None
+    if 'find_links' in opts:
+        find_links = _fixup_find_links(opts['find_links'][1])[:]
+    else:
+        find_links = []
+    if dist.dependency_links:
+        find_links.extend(dist.dependency_links)
+    eggs_dir = os.path.realpath(dist.get_egg_cache_dir())
+    environment = pkg_resources.Environment()
+    for egg_dist in pkg_resources.find_distributions(eggs_dir):
+        if egg_dist in req and environment.can_add(egg_dist):
+            return egg_dist
+    with TemporaryDirectory() as tmpdir:
+        cmd = [
+            sys.executable, '-m', 'pip',
+            '--disable-pip-version-check',
+            'wheel', '--no-deps',
+            '-w', tmpdir,
+        ]
+        if quiet:
+            cmd.append('--quiet')
+        if index_url is not None:
+            cmd.extend(('--index-url', index_url))
+        if find_links is not None:
+            for link in find_links:
+                cmd.extend(('--find-links', link))
+        # If requirement is a PEP 508 direct URL, directly pass
+        # the URL to pip, as `req @ url` does not work on the
+        # command line.
+        if req.url:
+            cmd.append(req.url)
+        else:
+            cmd.append(str(req))
+        try:
+            subprocess.check_call(cmd)
+        except subprocess.CalledProcessError as e:
+            raise DistutilsError(str(e))
+        wheel = Wheel(glob.glob(os.path.join(tmpdir, '*.whl'))[0])
+        dist_location = os.path.join(eggs_dir, wheel.egg_name())
+        wheel.install_as_egg(dist_location)
+        dist_metadata = pkg_resources.PathMetadata(
+            dist_location, os.path.join(dist_location, 'EGG-INFO'))
+        dist = pkg_resources.Distribution.from_filename(
+            dist_location, metadata=dist_metadata)
+        return dist
+
+
+def strip_marker(req):
+    """
+    Return a new requirement without the environment marker to avoid
+    calling pip with something like `babel; extra == "i18n"`, which
+    would always be ignored.
+    """
+    # create a copy to avoid mutating the input
+    req = pkg_resources.Requirement.parse(str(req))
+    req.marker = None
+    return req
diff --git a/setuptools/msvc.py b/setuptools/msvc.py
index 2ffe1c81..c2cbd1e5 100644
--- a/setuptools/msvc.py
+++ b/setuptools/msvc.py
@@ -544,7 +544,7 @@ class SystemInfo:
 
         # Except for VS15+, VC version is aligned with VS version
         self.vs_ver = self.vc_ver = (
-                vc_ver or self._find_latest_available_vs_ver())
+            vc_ver or self._find_latest_available_vs_ver())
 
     def _find_latest_available_vs_ver(self):
         """
@@ -1225,7 +1225,7 @@ class EnvironmentInfo:
             arch_subdir = self.pi.target_dir(x64=True)
             lib = join(self.si.WindowsSdkDir, 'lib')
             libver = self._sdk_subdir
-            return [join(lib, '%sum%s' % (libver , arch_subdir))]
+            return [join(lib, '%sum%s' % (libver, arch_subdir))]
 
     @property
     def OSIncludes(self):
@@ -1274,13 +1274,16 @@ class EnvironmentInfo:
             libpath += [
                 ref,
                 join(self.si.WindowsSdkDir, 'UnionMetadata'),
-                join(ref, 'Windows.Foundation.UniversalApiContract', '1.0.0.0'),
+                join(
+                    ref, 'Windows.Foundation.UniversalApiContract', '1.0.0.0'),
                 join(ref, 'Windows.Foundation.FoundationContract', '1.0.0.0'),
-                join(ref,'Windows.Networking.Connectivity.WwanContract',
-                     '1.0.0.0'),
-                join(self.si.WindowsSdkDir, 'ExtensionSDKs', 'Microsoft.VCLibs',
-                     '%0.1f' % self.vs_ver, 'References', 'CommonConfiguration',
-                     'neutral'),
+                join(
+                    ref, 'Windows.Networking.Connectivity.WwanContract',
+                    '1.0.0.0'),
+                join(
+                    self.si.WindowsSdkDir, 'ExtensionSDKs', 'Microsoft.VCLibs',
+                    '%0.1f' % self.vs_ver, 'References', 'CommonConfiguration',
+                    'neutral'),
             ]
         return libpath
 
diff --git a/setuptools/namespaces.py b/setuptools/namespaces.py
index dc16106d..5f403c96 100644
--- a/setuptools/namespaces.py
+++ b/setuptools/namespaces.py
@@ -47,13 +47,17 @@ class Installer:
         "p = os.path.join(%(root)s, *%(pth)r)",
         "importlib = has_mfs and __import__('importlib.util')",
         "has_mfs and __import__('importlib.machinery')",
-        "m = has_mfs and "
+        (
+            "m = has_mfs and "
             "sys.modules.setdefault(%(pkg)r, "
-                "importlib.util.module_from_spec("
-                    "importlib.machinery.PathFinder.find_spec(%(pkg)r, "
-                        "[os.path.dirname(p)])))",
-        "m = m or "
-            "sys.modules.setdefault(%(pkg)r, types.ModuleType(%(pkg)r))",
+            "importlib.util.module_from_spec("
+            "importlib.machinery.PathFinder.find_spec(%(pkg)r, "
+            "[os.path.dirname(p)])))"
+        ),
+        (
+            "m = m or "
+            "sys.modules.setdefault(%(pkg)r, types.ModuleType(%(pkg)r))"
+        ),
         "mp = (m or []) and m.__dict__.setdefault('__path__',[])",
         "(p not in mp) and mp.append(p)",
     )
diff --git a/setuptools/package_index.py b/setuptools/package_index.py
index f419d471..82eb4516 100644
--- a/setuptools/package_index.py
+++ b/setuptools/package_index.py
@@ -46,7 +46,8 @@ __all__ = [
 _SOCKET_TIMEOUT = 15
 
 _tmpl = "setuptools/{setuptools.__version__} Python-urllib/{py_major}"
-user_agent = _tmpl.format(py_major='{}.{}'.format(*sys.version_info), setuptools=setuptools)
+user_agent = _tmpl.format(
+    py_major='{}.{}'.format(*sys.version_info), setuptools=setuptools)
 
 
 def parse_requirement_arg(spec):
@@ -1092,7 +1093,8 @@ def open_with_auth(url, opener=urllib.request.urlopen):
 
 # copy of urllib.parse._splituser from Python 3.8
 def _splituser(host):
-    """splituser('user[:passwd]@host[:port]') --> 'user[:passwd]', 'host[:port]'."""
+    """splituser('user[:passwd]@host[:port]')
+    --> 'user[:passwd]', 'host[:port]'."""
     user, delim, host = host.rpartition('@')
     return (user if delim else None), host
 
diff --git a/setuptools/pep425tags.py b/setuptools/pep425tags.py
deleted file mode 100644
index 48745a29..00000000
--- a/setuptools/pep425tags.py
+++ /dev/null
@@ -1,319 +0,0 @@
-# This file originally from pip:
-# https://github.com/pypa/pip/blob/8f4f15a5a95d7d5b511ceaee9ed261176c181970/src/pip/_internal/pep425tags.py
-"""Generate and work with PEP 425 Compatibility Tags."""
-from __future__ import absolute_import
-
-import distutils.util
-from distutils import log
-import platform
-import re
-import sys
-import sysconfig
-import warnings
-from collections import OrderedDict
-
-from .extern import six
-
-from . import glibc
-
-_osx_arch_pat = re.compile(r'(.+)_(\d+)_(\d+)_(.+)')
-
-
-def get_config_var(var):
-    try:
-        return sysconfig.get_config_var(var)
-    except IOError as e:  # Issue #1074
-        warnings.warn("{}".format(e), RuntimeWarning)
-        return None
-
-
-def get_abbr_impl():
-    """Return abbreviated implementation name."""
-    if hasattr(sys, 'pypy_version_info'):
-        pyimpl = 'pp'
-    elif sys.platform.startswith('java'):
-        pyimpl = 'jy'
-    elif sys.platform == 'cli':
-        pyimpl = 'ip'
-    else:
-        pyimpl = 'cp'
-    return pyimpl
-
-
-def get_impl_ver():
-    """Return implementation version."""
-    impl_ver = get_config_var("py_version_nodot")
-    if not impl_ver or get_abbr_impl() == 'pp':
-        impl_ver = ''.join(map(str, get_impl_version_info()))
-    return impl_ver
-
-
-def get_impl_version_info():
-    """Return sys.version_info-like tuple for use in decrementing the minor
-    version."""
-    if get_abbr_impl() == 'pp':
-        # as per https://github.com/pypa/pip/issues/2882
-        return (sys.version_info[0], sys.pypy_version_info.major,
-                sys.pypy_version_info.minor)
-    else:
-        return sys.version_info[0], sys.version_info[1]
-
-
-def get_impl_tag():
-    """
-    Returns the Tag for this specific implementation.
-    """
-    return "{}{}".format(get_abbr_impl(), get_impl_ver())
-
-
-def get_flag(var, fallback, expected=True, warn=True):
-    """Use a fallback method for determining SOABI flags if the needed config
-    var is unset or unavailable."""
-    val = get_config_var(var)
-    if val is None:
-        if warn:
-            log.debug("Config variable '%s' is unset, Python ABI tag may "
-                      "be incorrect", var)
-        return fallback()
-    return val == expected
-
-
-def get_abi_tag():
-    """Return the ABI tag based on SOABI (if available) or emulate SOABI
-    (CPython 2, PyPy)."""
-    soabi = get_config_var('SOABI')
-    impl = get_abbr_impl()
-    if not soabi and impl in {'cp', 'pp'} and hasattr(sys, 'maxunicode'):
-        d = ''
-        m = ''
-        u = ''
-        if get_flag('Py_DEBUG',
-                    lambda: hasattr(sys, 'gettotalrefcount'),
-                    warn=(impl == 'cp')):
-            d = 'd'
-        if get_flag('WITH_PYMALLOC',
-                    lambda: impl == 'cp',
-                    warn=(impl == 'cp')):
-            m = 'm'
-        if get_flag('Py_UNICODE_SIZE',
-                    lambda: sys.maxunicode == 0x10ffff,
-                    expected=4,
-                    warn=(impl == 'cp' and
-                          six.PY2)) \
-                and six.PY2:
-            u = 'u'
-        abi = '%s%s%s%s%s' % (impl, get_impl_ver(), d, m, u)
-    elif soabi and soabi.startswith('cpython-'):
-        abi = 'cp' + soabi.split('-')[1]
-    elif soabi:
-        abi = soabi.replace('.', '_').replace('-', '_')
-    else:
-        abi = None
-    return abi
-
-
-def _is_running_32bit():
-    return sys.maxsize == 2147483647
-
-
-def get_platform():
-    """Return our platform name 'win32', 'linux_x86_64'"""
-    if sys.platform == 'darwin':
-        # distutils.util.get_platform() returns the release based on the value
-        # of MACOSX_DEPLOYMENT_TARGET on which Python was built, which may
-        # be significantly older than the user's current machine.
-        release, _, machine = platform.mac_ver()
-        split_ver = release.split('.')
-
-        if machine == "x86_64" and _is_running_32bit():
-            machine = "i386"
-        elif machine == "ppc64" and _is_running_32bit():
-            machine = "ppc"
-
-        return 'macosx_{}_{}_{}'.format(split_ver[0], split_ver[1], machine)
-
-    # XXX remove distutils dependency
-    result = distutils.util.get_platform().replace('.', '_').replace('-', '_')
-    if result == "linux_x86_64" and _is_running_32bit():
-        # 32 bit Python program (running on a 64 bit Linux): pip should only
-        # install and run 32 bit compiled extensions in that case.
-        result = "linux_i686"
-
-    return result
-
-
-def is_manylinux1_compatible():
-    # Only Linux, and only x86-64 / i686
-    if get_platform() not in {"linux_x86_64", "linux_i686"}:
-        return False
-
-    # Check for presence of _manylinux module
-    try:
-        import _manylinux
-        return bool(_manylinux.manylinux1_compatible)
-    except (ImportError, AttributeError):
-        # Fall through to heuristic check below
-        pass
-
-    # Check glibc version. CentOS 5 uses glibc 2.5.
-    return glibc.have_compatible_glibc(2, 5)
-
-
-def get_darwin_arches(major, minor, machine):
-    """Return a list of supported arches (including group arches) for
-    the given major, minor and machine architecture of a macOS machine.
-    """
-    arches = []
-
-    def _supports_arch(major, minor, arch):
-        # Looking at the application support for macOS versions in the chart
-        # provided by https://en.wikipedia.org/wiki/OS_X#Versions it appears
-        # our timeline looks roughly like:
-        #
-        # 10.0 - Introduces ppc support.
-        # 10.4 - Introduces ppc64, i386, and x86_64 support, however the ppc64
-        #        and x86_64 support is CLI only, and cannot be used for GUI
-        #        applications.
-        # 10.5 - Extends ppc64 and x86_64 support to cover GUI applications.
-        # 10.6 - Drops support for ppc64
-        # 10.7 - Drops support for ppc
-        #
-        # Given that we do not know if we're installing a CLI or a GUI
-        # application, we must be conservative and assume it might be a GUI
-        # application and behave as if ppc64 and x86_64 support did not occur
-        # until 10.5.
-        #
-        # Note: The above information is taken from the "Application support"
-        #       column in the chart not the "Processor support" since I believe
-        #       that we care about what instruction sets an application can use
-        #       not which processors the OS supports.
-        if arch == 'ppc':
-            return (major, minor) <= (10, 5)
-        if arch == 'ppc64':
-            return (major, minor) == (10, 5)
-        if arch == 'i386':
-            return (major, minor) >= (10, 4)
-        if arch == 'x86_64':
-            return (major, minor) >= (10, 5)
-        if arch in groups:
-            for garch in groups[arch]:
-                if _supports_arch(major, minor, garch):
-                    return True
-        return False
-
-    groups = OrderedDict([
-        ("fat", ("i386", "ppc")),
-        ("intel", ("x86_64", "i386")),
-        ("fat64", ("x86_64", "ppc64")),
-        ("fat32", ("x86_64", "i386", "ppc")),
-    ])
-
-    if _supports_arch(major, minor, machine):
-        arches.append(machine)
-
-    for garch in groups:
-        if machine in groups[garch] and _supports_arch(major, minor, garch):
-            arches.append(garch)
-
-    arches.append('universal')
-
-    return arches
-
-
-def get_supported(versions=None, noarch=False, platform=None,
-                  impl=None, abi=None):
-    """Return a list of supported tags for each version specified in
-    `versions`.
-
-    :param versions: a list of string versions, of the form ["33", "32"],
-        or None. The first version will be assumed to support our ABI.
-    :param platform: specify the exact platform you want valid
-        tags for, or None. If None, use the local system platform.
-    :param impl: specify the exact implementation you want valid
-        tags for, or None. If None, use the local interpreter impl.
-    :param abi: specify the exact abi you want valid
-        tags for, or None. If None, use the local interpreter abi.
-    """
-    supported = []
-
-    # Versions must be given with respect to the preference
-    if versions is None:
-        versions = []
-        version_info = get_impl_version_info()
-        major = version_info[:-1]
-        # Support all previous minor Python versions.
-        for minor in range(version_info[-1], -1, -1):
-            versions.append(''.join(map(str, major + (minor,))))
-
-    impl = impl or get_abbr_impl()
-
-    abis = []
-
-    abi = abi or get_abi_tag()
-    if abi:
-        abis[0:0] = [abi]
-
-    abi3s = set()
-    import imp
-    for suffix in imp.get_suffixes():
-        if suffix[0].startswith('.abi'):
-            abi3s.add(suffix[0].split('.', 2)[1])
-
-    abis.extend(sorted(list(abi3s)))
-
-    abis.append('none')
-
-    if not noarch:
-        arch = platform or get_platform()
-        if arch.startswith('macosx'):
-            # support macosx-10.6-intel on macosx-10.9-x86_64
-            match = _osx_arch_pat.match(arch)
-            if match:
-                name, major, minor, actual_arch = match.groups()
-                tpl = '{}_{}_%i_%s'.format(name, major)
-                arches = []
-                for m in reversed(range(int(minor) + 1)):
-                    for a in get_darwin_arches(int(major), m, actual_arch):
-                        arches.append(tpl % (m, a))
-            else:
-                # arch pattern didn't match (?!)
-                arches = [arch]
-        elif platform is None and is_manylinux1_compatible():
-            arches = [arch.replace('linux', 'manylinux1'), arch]
-        else:
-            arches = [arch]
-
-        # Current version, current API (built specifically for our Python):
-        for abi in abis:
-            for arch in arches:
-                supported.append(('%s%s' % (impl, versions[0]), abi, arch))
-
-        # abi3 modules compatible with older version of Python
-        for version in versions[1:]:
-            # abi3 was introduced in Python 3.2
-            if version in {'31', '30'}:
-                break
-            for abi in abi3s:   # empty set if not Python 3
-                for arch in arches:
-                    supported.append(("%s%s" % (impl, version), abi, arch))
-
-        # Has binaries, does not use the Python API:
-        for arch in arches:
-            supported.append(('py%s' % (versions[0][0]), 'none', arch))
-
-    # No abi / arch, but requires our implementation:
-    supported.append(('%s%s' % (impl, versions[0]), 'none', 'any'))
-    # Tagged specifically as being cross-version compatible
-    # (with just the major version specified)
-    supported.append(('%s%s' % (impl, versions[0][0]), 'none', 'any'))
-
-    # No abi / arch, generic Python
-    for i, version in enumerate(versions):
-        supported.append(('py%s' % (version,), 'none', 'any'))
-        if i == 0:
-            supported.append(('py%s' % (version[0]), 'none', 'any'))
-
-    return supported
-
-
-implementation_tag = get_impl_tag()
diff --git a/setuptools/py27compat.py b/setuptools/py27compat.py
index 1d57360f..ba39af52 100644
--- a/setuptools/py27compat.py
+++ b/setuptools/py27compat.py
@@ -16,7 +16,7 @@ def get_all_headers(message, key):
 
 
 if six.PY2:
-    def get_all_headers(message, key):
+    def get_all_headers(message, key):  # noqa
         return message.getheaders(key)
 
 
diff --git a/setuptools/sandbox.py b/setuptools/sandbox.py
index 685f3f72..e46dfc8d 100644
--- a/setuptools/sandbox.py
+++ b/setuptools/sandbox.py
@@ -13,6 +13,8 @@ from setuptools.extern import six
 from setuptools.extern.six.moves import builtins, map
 
 import pkg_resources.py31compat
+from distutils.errors import DistutilsError
+from pkg_resources import working_set
 
 if sys.platform.startswith('java'):
     import org.python.modules.posix.PosixModule as _os
@@ -23,8 +25,6 @@ try:
 except NameError:
     _file = None
 _open = open
-from distutils.errors import DistutilsError
-from pkg_resources import working_set
 
 
 __all__ = [
@@ -374,7 +374,7 @@ class AbstractSandbox:
 
 
 if hasattr(os, 'devnull'):
-    _EXCEPTIONS = [os.devnull,]
+    _EXCEPTIONS = [os.devnull]
 else:
     _EXCEPTIONS = []
 
@@ -466,7 +466,8 @@ class DirectorySandbox(AbstractSandbox):
 
 
 WRITE_FLAGS = functools.reduce(
-    operator.or_, [getattr(_os, a, 0) for a in
+    operator.or_, [
+        getattr(_os, a, 0) for a in
         "O_WRONLY O_RDWR O_APPEND O_CREAT O_TRUNC O_TEMPORARY".split()]
 )
 
diff --git a/setuptools/site-patch.py b/setuptools/site-patch.py
index 40b00de0..be0d43d3 100644
--- a/setuptools/site-patch.py
+++ b/setuptools/site-patch.py
@@ -38,22 +38,24 @@ def __boot():
     else:
         raise ImportError("Couldn't find the real 'site' module")
 
-    known_paths = dict([(makepath(item)[1], 1) for item in sys.path])  # 2.2 comp
+    # 2.2 comp
+    known_paths = dict([(
+        makepath(item)[1], 1) for item in sys.path])  # noqa
 
     oldpos = getattr(sys, '__egginsert', 0)  # save old insertion position
     sys.__egginsert = 0  # and reset the current one
 
     for item in PYTHONPATH:
-        addsitedir(item)
+        addsitedir(item)  # noqa
 
     sys.__egginsert += oldpos  # restore effective old position
 
-    d, nd = makepath(stdpath[0])
+    d, nd = makepath(stdpath[0])  # noqa
     insert_at = None
     new_path = []
 
     for item in sys.path:
-        p, np = makepath(item)
+        p, np = makepath(item)  # noqa
 
         if np == nd and insert_at is None:
             # We've hit the first 'system' path entry, so added entries go here
diff --git a/setuptools/ssl_support.py b/setuptools/ssl_support.py
index 226db694..17c14c46 100644
--- a/setuptools/ssl_support.py
+++ b/setuptools/ssl_support.py
@@ -35,7 +35,8 @@ try:
 except AttributeError:
     HTTPSHandler = HTTPSConnection = object
 
-is_available = ssl is not None and object not in (HTTPSHandler, HTTPSConnection)
+is_available = ssl is not None and object not in (
+    HTTPSHandler, HTTPSConnection)
 
 
 try:
@@ -85,8 +86,10 @@ if not match_hostname:
             return dn.lower() == hostname.lower()
 
         # RFC 6125, section 6.4.3, subitem 1.
-        # The client SHOULD NOT attempt to match a presented identifier in which
-        # the wildcard character comprises a label other than the left-most label.
+        # The client SHOULD NOT attempt to match a
+        # presented identifier in which the wildcard
+        # character comprises a label other than the
+        # left-most label.
         if leftmost == '*':
             # When '*' is a fragment by itself, it matches a non-empty dotless
             # fragment.
@@ -137,15 +140,16 @@ if not match_hostname:
                             return
                         dnsnames.append(value)
         if len(dnsnames) > 1:
-            raise CertificateError("hostname %r "
-                "doesn't match either of %s"
+            raise CertificateError(
+                "hostname %r doesn't match either of %s"
                 % (hostname, ', '.join(map(repr, dnsnames))))
         elif len(dnsnames) == 1:
-            raise CertificateError("hostname %r "
-                "doesn't match %r"
+            raise CertificateError(
+                "hostname %r doesn't match %r"
                 % (hostname, dnsnames[0]))
         else:
-            raise CertificateError("no appropriate commonName or "
+            raise CertificateError(
+                "no appropriate commonName or "
                 "subjectAltName fields were found")
 
 
@@ -158,7 +162,8 @@ class VerifyingHTTPSHandler(HTTPSHandler):
 
     def https_open(self, req):
         return self.do_open(
-            lambda host, **kw: VerifyingHTTPSConn(host, self.ca_bundle, **kw), req
+            lambda host, **kw: VerifyingHTTPSConn(host, self.ca_bundle, **kw),
+            req
         )
 
 
diff --git a/setuptools/tests/__init__.py b/setuptools/tests/__init__.py
index 5f4a1c29..9c77b51f 100644
--- a/setuptools/tests/__init__.py
+++ b/setuptools/tests/__init__.py
@@ -6,7 +6,7 @@ from setuptools.extern.six import PY2, PY3
 
 
 __all__ = [
-  'fail_on_ascii', 'py2_only', 'py3_only'
+    'fail_on_ascii', 'py2_only', 'py3_only'
 ]
 
 
diff --git a/setuptools/tests/server.py b/setuptools/tests/server.py
index fc3a5975..8b17b081 100644
--- a/setuptools/tests/server.py
+++ b/setuptools/tests/server.py
@@ -1,10 +1,13 @@
 """Basic http server for tests to simulate PyPI or custom indexes
 """
 
+import os
 import time
 import threading
 
 from setuptools.extern.six.moves import BaseHTTPServer, SimpleHTTPServer
+from setuptools.extern.six.moves.urllib_parse import urljoin
+from setuptools.extern.six.moves.urllib.request import pathname2url
 
 
 class IndexServer(BaseHTTPServer.HTTPServer):
@@ -70,5 +73,19 @@ class MockServer(BaseHTTPServer.HTTPServer, threading.Thread):
         self.serve_forever()
 
     @property
+    def netloc(self):
+        return 'localhost:%s' % self.server_port
+
+    @property
     def url(self):
-        return 'http://localhost:%(server_port)s/' % vars(self)
+        return 'http://%s/' % self.netloc
+
+
+def path_to_url(path, authority=None):
+    """ Convert a path to a file: URL. """
+    path = os.path.normpath(os.path.abspath(path))
+    base = 'file:'
+    if authority is not None:
+        base += '//' + authority
+    url = urljoin(base, pathname2url(path))
+    return url
diff --git a/setuptools/tests/test_build_clib.py b/setuptools/tests/test_build_clib.py
index 3779e679..48bea2b4 100644
--- a/setuptools/tests/test_build_clib.py
+++ b/setuptools/tests/test_build_clib.py
@@ -8,8 +8,7 @@ from setuptools.dist import Distribution
 
 class TestBuildCLib:
     @mock.patch(
-            'setuptools.command.build_clib.newer_pairwise_group'
-            )
+        'setuptools.command.build_clib.newer_pairwise_group')
     def test_build_libraries(self, mock_newer):
         dist = Distribution()
         cmd = build_clib(dist)
diff --git a/setuptools/tests/test_build_meta.py b/setuptools/tests/test_build_meta.py
index e1efe561..8fcf3055 100644
--- a/setuptools/tests/test_build_meta.py
+++ b/setuptools/tests/test_build_meta.py
@@ -23,6 +23,7 @@ class BuildBackendBase:
         self.env = env
         self.backend_name = backend_name
 
+
 class BuildBackend(BuildBackendBase):
     """PEP 517 Build Backend"""
 
@@ -262,6 +263,27 @@ class TestBuildMetaBackend:
         assert os.path.isfile(
             os.path.join(os.path.abspath("out_sdist"), sdist_name))
 
+    def test_build_sdist_pyproject_toml_exists(self, tmpdir_cwd):
+        files = {
+            'setup.py': DALS("""
+                __import__('setuptools').setup(
+                    name='foo',
+                    version='0.0.0',
+                    py_modules=['hello']
+                )"""),
+            'hello.py': '',
+            'pyproject.toml': DALS("""
+                [build-system]
+                requires = ["setuptools", "wheel"]
+                build-backend = "setuptools.build_meta
+                """),
+        }
+        build_files(files)
+        build_backend = self.get_build_backend()
+        targz_path = build_backend.build_sdist("temp")
+        with tarfile.open(os.path.join("temp", targz_path)) as tar:
+            assert any('pyproject.toml' in name for name in tar.getnames())
+
     def test_build_sdist_setup_py_exists(self, tmpdir_cwd):
         # If build_sdist is called from a script other than setup.py,
         # ensure setup.py is included
@@ -385,6 +407,28 @@ class TestBuildMetaBackend:
 
         assert expected == sorted(actual)
 
+    _sys_argv_0_passthrough = {
+        'setup.py': DALS("""
+            import os
+            import sys
+
+            __import__('setuptools').setup(
+                name='foo',
+                version='0.0.0',
+            )
+
+            sys_argv = os.path.abspath(sys.argv[0])
+            file_path = os.path.abspath('setup.py')
+            assert sys_argv == file_path
+            """)
+    }
+
+    def test_sys_argv_passthrough(self, tmpdir_cwd):
+        build_files(self._sys_argv_0_passthrough)
+        build_backend = self.get_build_backend()
+        with pytest.raises(AssertionError):
+            build_backend.build_sdist("temp")
+
 
 class TestBuildMetaLegacyBackend(TestBuildMetaBackend):
     backend_name = 'setuptools.build_meta:__legacy__'
@@ -396,3 +440,9 @@ class TestBuildMetaLegacyBackend(TestBuildMetaBackend):
 
         build_backend = self.get_build_backend()
         build_backend.build_sdist("temp")
+
+    def test_sys_argv_passthrough(self, tmpdir_cwd):
+        build_files(self._sys_argv_0_passthrough)
+
+        build_backend = self.get_build_backend()
+        build_backend.build_sdist("temp")
diff --git a/setuptools/tests/test_config.py b/setuptools/tests/test_config.py
index 69d8d00d..2fa0b374 100644
--- a/setuptools/tests/test_config.py
+++ b/setuptools/tests/test_config.py
@@ -695,7 +695,7 @@ class TestOptions:
         )
         with get_dist(tmpdir) as dist:
             assert set(dist.packages) == set(
-                ['fake_package',  'fake_package.sub_two'])
+                ['fake_package', 'fake_package.sub_two'])
 
     @py2_only
     def test_find_namespace_directive_fails_on_py2(self, tmpdir):
@@ -748,7 +748,7 @@ class TestOptions:
         )
         with get_dist(tmpdir) as dist:
             assert set(dist.packages) == {
-                'fake_package',  'fake_package.sub_two'
+                'fake_package', 'fake_package.sub_two'
             }
 
     def test_extras_require(self, tmpdir):
@@ -881,7 +881,7 @@ class TestExternalSetters:
         return None
 
     @patch.object(_Distribution, '__init__', autospec=True)
-    def test_external_setters(self,  mock_parent_init, tmpdir):
+    def test_external_setters(self, mock_parent_init, tmpdir):
         mock_parent_init.side_effect = self._fake_distribution_init
 
         dist = Distribution(attrs={
diff --git a/setuptools/tests/test_develop.py b/setuptools/tests/test_develop.py
index 00d4bd9a..792975fd 100644
--- a/setuptools/tests/test_develop.py
+++ b/setuptools/tests/test_develop.py
@@ -95,7 +95,7 @@ class TestDevelop:
         with io.open(fn) as init_file:
             init = init_file.read().strip()
 
-        expected = 'print("foo")' if six.PY3 else 'print "foo"'
+        expected = 'print "foo"' if six.PY2 else 'print("foo")'
         assert init == expected
 
     def test_console_scripts(self, tmpdir):
@@ -161,7 +161,7 @@ class TestNamespaces:
         reason="https://github.com/pypa/setuptools/issues/851",
     )
     @pytest.mark.skipif(
-        platform.python_implementation() == 'PyPy' and six.PY3,
+        platform.python_implementation() == 'PyPy' and not six.PY2,
         reason="https://github.com/pypa/setuptools/issues/1202",
     )
     def test_namespace_package_importable(self, tmpdir):
diff --git a/setuptools/tests/test_dist.py b/setuptools/tests/test_dist.py
index 36237f24..b93ef148 100644
--- a/setuptools/tests/test_dist.py
+++ b/setuptools/tests/test_dist.py
@@ -284,7 +284,7 @@ def test_provides_extras_deterministic_order():
     dist = Distribution(attrs)
     assert dist.metadata.provides_extras == ['b', 'a']
 
-   
+
 CHECK_PACKAGE_DATA_TESTS = (
     # Valid.
     ({
@@ -309,7 +309,8 @@ CHECK_PACKAGE_DATA_TESTS = (
     ({
         'hello': str('*.msg'),
     }, (
-        "\"values of 'package_data' dict\" must be a list of strings (got '*.msg')"
+        "\"values of 'package_data' dict\" "
+        "must be a list of strings (got '*.msg')"
     )),
     # Invalid value type (generators are single use)
     ({
@@ -321,10 +322,12 @@ CHECK_PACKAGE_DATA_TESTS = (
 )
 
 
-@pytest.mark.parametrize('package_data, expected_message', CHECK_PACKAGE_DATA_TESTS)
+@pytest.mark.parametrize(
+    'package_data, expected_message', CHECK_PACKAGE_DATA_TESTS)
 def test_check_package_data(package_data, expected_message):
     if expected_message is None:
         assert check_package_data(None, 'package_data', package_data) is None
     else:
-        with pytest.raises(DistutilsSetupError, match=re.escape(expected_message)):
+        with pytest.raises(
+                DistutilsSetupError, match=re.escape(expected_message)):
             check_package_data(None, str('package_data'), package_data)
diff --git a/setuptools/tests/test_easy_install.py b/setuptools/tests/test_easy_install.py
index c3fd1c6e..534392b9 100644
--- a/setuptools/tests/test_easy_install.py
+++ b/setuptools/tests/test_easy_install.py
@@ -15,28 +15,29 @@ import distutils.errors
 import io
 import zipfile
 import mock
-from setuptools.command.easy_install import (
-    EasyInstallDeprecationWarning, ScriptWriter, WindowsScriptWriter,
-)
 import time
+
 from setuptools.extern import six
-from setuptools.extern.six.moves import urllib
 
 import pytest
 
 from setuptools import sandbox
 from setuptools.sandbox import run_setup
 import setuptools.command.easy_install as ei
-from setuptools.command.easy_install import PthDistributions
+from setuptools.command.easy_install import (
+    EasyInstallDeprecationWarning, ScriptWriter, PthDistributions,
+    WindowsScriptWriter,
+)
 from setuptools.command import easy_install as easy_install_pkg
 from setuptools.dist import Distribution
 from pkg_resources import normalize_path, working_set
 from pkg_resources import Distribution as PRDistribution
-import setuptools.tests.server
+from setuptools.tests.server import MockServer, path_to_url
 from setuptools.tests import fail_on_ascii
 import pkg_resources
 
 from . import contexts
+from .files import build_files
 from .textwrap import DALS
 
 __metaclass__ = type
@@ -440,35 +441,40 @@ def distutils_package():
         yield
 
 
+@pytest.fixture
+def mock_index():
+    # set up a server which will simulate an alternate package index.
+    p_index = MockServer()
+    if p_index.server_port == 0:
+        # Some platforms (Jython) don't find a port to which to bind,
+        # so skip test for them.
+        pytest.skip("could not find a valid port")
+    p_index.start()
+    return p_index
+
+
 class TestDistutilsPackage:
     def test_bdist_egg_available_on_distutils_pkg(self, distutils_package):
         run_setup('setup.py', ['bdist_egg'])
 
 
 class TestSetupRequires:
-    def test_setup_requires_honors_fetch_params(self):
+
+    def test_setup_requires_honors_fetch_params(self, mock_index, monkeypatch):
         """
         When easy_install installs a source distribution which specifies
         setup_requires, it should honor the fetch parameters (such as
-        allow-hosts, index-url, and find-links).
+        index-url, and find-links).
         """
-        # set up a server which will simulate an alternate package index.
-        p_index = setuptools.tests.server.MockServer()
-        p_index.start()
-        netloc = 1
-        p_index_loc = urllib.parse.urlparse(p_index.url)[netloc]
-        if p_index_loc.endswith(':0'):
-            # Some platforms (Jython) don't find a port to which to bind,
-            #  so skip this test for them.
-            return
+        monkeypatch.setenv(str('PIP_RETRIES'), str('0'))
+        monkeypatch.setenv(str('PIP_TIMEOUT'), str('0'))
         with contexts.quiet():
             # create an sdist that has a build-time dependency.
             with TestSetupRequires.create_sdist() as dist_file:
                 with contexts.tempdir() as temp_install_dir:
                     with contexts.environment(PYTHONPATH=temp_install_dir):
                         ei_params = [
-                            '--index-url', p_index.url,
-                            '--allow-hosts', p_index_loc,
+                            '--index-url', mock_index.url,
                             '--exclude-scripts',
                             '--install-dir', temp_install_dir,
                             dist_file,
@@ -478,10 +484,8 @@ class TestSetupRequires:
                             # fail because it doesn't exist.
                             with pytest.raises(SystemExit):
                                 easy_install_pkg.main(ei_params)
-        # there should have been two or three requests to the server
-        #  (three happens on Python 3.3a)
-        assert 2 <= len(p_index.requests) <= 3
-        assert p_index.requests[0].path == '/does-not-exist/'
+        # there should have been one requests to the server
+        assert [r.path for r in mock_index.requests] == ['/does-not-exist/']
 
     @staticmethod
     @contextlib.contextmanager
@@ -500,7 +504,9 @@ class TestSetupRequires:
                         version="1.0",
                         setup_requires = ['does-not-exist'],
                     )
-                """))])
+                """)),
+                ('setup.cfg', ''),
+            ])
             yield dist_path
 
     use_setup_cfg = (
@@ -623,7 +629,7 @@ class TestSetupRequires:
                 test_pkg = create_setup_requires_package(
                     temp_dir, setup_attrs=dict(version='attr: foobar.version'),
                     make_package=make_dependency_sdist,
-                    use_setup_cfg=use_setup_cfg+('version',),
+                    use_setup_cfg=use_setup_cfg + ('version',),
                 )
                 test_setup_py = os.path.join(test_pkg, 'setup.py')
                 with contexts.quiet() as (stdout, stderr):
@@ -632,6 +638,208 @@ class TestSetupRequires:
                 assert len(lines) > 0
                 assert lines[-1].strip() == '42'
 
+    def test_setup_requires_honors_pip_env(self, mock_index, monkeypatch):
+        monkeypatch.setenv(str('PIP_RETRIES'), str('0'))
+        monkeypatch.setenv(str('PIP_TIMEOUT'), str('0'))
+        monkeypatch.setenv(str('PIP_INDEX_URL'), mock_index.url)
+        with contexts.save_pkg_resources_state():
+            with contexts.tempdir() as temp_dir:
+                test_pkg = create_setup_requires_package(
+                    temp_dir, 'python-xlib', '0.19',
+                    setup_attrs=dict(dependency_links=[]))
+                test_setup_cfg = os.path.join(test_pkg, 'setup.cfg')
+                with open(test_setup_cfg, 'w') as fp:
+                    fp.write(DALS(
+                        '''
+                        [easy_install]
+                        index_url = https://pypi.org/legacy/
+                        '''))
+                test_setup_py = os.path.join(test_pkg, 'setup.py')
+                with pytest.raises(distutils.errors.DistutilsError):
+                    run_setup(test_setup_py, [str('--version')])
+        assert len(mock_index.requests) == 1
+        assert mock_index.requests[0].path == '/python-xlib/'
+
+    def test_setup_requires_with_pep508_url(self, mock_index, monkeypatch):
+        monkeypatch.setenv(str('PIP_RETRIES'), str('0'))
+        monkeypatch.setenv(str('PIP_TIMEOUT'), str('0'))
+        monkeypatch.setenv(str('PIP_INDEX_URL'), mock_index.url)
+        with contexts.save_pkg_resources_state():
+            with contexts.tempdir() as temp_dir:
+                dep_sdist = os.path.join(temp_dir, 'dep.tar.gz')
+                make_trivial_sdist(dep_sdist, 'dependency', '42')
+                dep_url = path_to_url(dep_sdist, authority='localhost')
+                test_pkg = create_setup_requires_package(
+                    temp_dir,
+                    # Ignored (overriden by setup_attrs)
+                    'python-xlib', '0.19',
+                    setup_attrs=dict(
+                        setup_requires='dependency @ %s' % dep_url))
+                test_setup_py = os.path.join(test_pkg, 'setup.py')
+                run_setup(test_setup_py, [str('--version')])
+        assert len(mock_index.requests) == 0
+
+    def test_setup_requires_with_allow_hosts(self, mock_index):
+        ''' The `allow-hosts` option in not supported anymore. '''
+        with contexts.save_pkg_resources_state():
+            with contexts.tempdir() as temp_dir:
+                test_pkg = os.path.join(temp_dir, 'test_pkg')
+                test_setup_py = os.path.join(test_pkg, 'setup.py')
+                test_setup_cfg = os.path.join(test_pkg, 'setup.cfg')
+                os.mkdir(test_pkg)
+                with open(test_setup_py, 'w') as fp:
+                    fp.write(DALS(
+                        '''
+                        from setuptools import setup
+                        setup(setup_requires='python-xlib')
+                        '''))
+                with open(test_setup_cfg, 'w') as fp:
+                    fp.write(DALS(
+                        '''
+                        [easy_install]
+                        allow_hosts = *
+                        '''))
+                with pytest.raises(distutils.errors.DistutilsError):
+                    run_setup(test_setup_py, [str('--version')])
+        assert len(mock_index.requests) == 0
+
+    def test_setup_requires_with_python_requires(self, monkeypatch, tmpdir):
+        ''' Check `python_requires` is honored. '''
+        monkeypatch.setenv(str('PIP_RETRIES'), str('0'))
+        monkeypatch.setenv(str('PIP_TIMEOUT'), str('0'))
+        monkeypatch.setenv(str('PIP_NO_INDEX'), str('1'))
+        monkeypatch.setenv(str('PIP_VERBOSE'), str('1'))
+        dep_1_0_sdist = 'dep-1.0.tar.gz'
+        dep_1_0_url = path_to_url(str(tmpdir / dep_1_0_sdist))
+        dep_1_0_python_requires = '>=2.7'
+        make_python_requires_sdist(
+            str(tmpdir / dep_1_0_sdist), 'dep', '1.0', dep_1_0_python_requires)
+        dep_2_0_sdist = 'dep-2.0.tar.gz'
+        dep_2_0_url = path_to_url(str(tmpdir / dep_2_0_sdist))
+        dep_2_0_python_requires = '!=' + '.'.join(
+            map(str, sys.version_info[:2])) + '.*'
+        make_python_requires_sdist(
+            str(tmpdir / dep_2_0_sdist), 'dep', '2.0', dep_2_0_python_requires)
+        index = tmpdir / 'index.html'
+        index.write_text(DALS(
+            '''
+            <!DOCTYPE html>
+            <html><head><title>Links for dep</title></head>
+            <body>
+                <h1>Links for dep</h1>
+                <a href="{dep_1_0_url}" data-requires-python="{dep_1_0_python_requires}">{dep_1_0_sdist}</a><br/>
+                <a href="{dep_2_0_url}" data-requires-python="{dep_2_0_python_requires}">{dep_2_0_sdist}</a><br/>
+            </body>
+            </html>
+            ''').format(  # noqa
+                dep_1_0_url=dep_1_0_url,
+                dep_1_0_sdist=dep_1_0_sdist,
+                dep_1_0_python_requires=dep_1_0_python_requires,
+                dep_2_0_url=dep_2_0_url,
+                dep_2_0_sdist=dep_2_0_sdist,
+                dep_2_0_python_requires=dep_2_0_python_requires,
+            ), 'utf-8')
+        index_url = path_to_url(str(index))
+        with contexts.save_pkg_resources_state():
+            test_pkg = create_setup_requires_package(
+                str(tmpdir),
+                'python-xlib', '0.19',  # Ignored (overriden by setup_attrs).
+                setup_attrs=dict(
+                    setup_requires='dep', dependency_links=[index_url]))
+            test_setup_py = os.path.join(test_pkg, 'setup.py')
+            run_setup(test_setup_py, [str('--version')])
+        eggs = list(map(str, pkg_resources.find_distributions(
+            os.path.join(test_pkg, '.eggs'))))
+        assert eggs == ['dep 1.0']
+
+    @pytest.mark.parametrize(
+        'use_legacy_installer,with_dependency_links_in_setup_py',
+        itertools.product((False, True), (False, True)))
+    def test_setup_requires_with_find_links_in_setup_cfg(
+            self, monkeypatch, use_legacy_installer,
+            with_dependency_links_in_setup_py):
+        monkeypatch.setenv(str('PIP_RETRIES'), str('0'))
+        monkeypatch.setenv(str('PIP_TIMEOUT'), str('0'))
+        with contexts.save_pkg_resources_state():
+            with contexts.tempdir() as temp_dir:
+                make_trivial_sdist(
+                    os.path.join(temp_dir, 'python-xlib-42.tar.gz'),
+                    'python-xlib',
+                    '42')
+                test_pkg = os.path.join(temp_dir, 'test_pkg')
+                test_setup_py = os.path.join(test_pkg, 'setup.py')
+                test_setup_cfg = os.path.join(test_pkg, 'setup.cfg')
+                os.mkdir(test_pkg)
+                with open(test_setup_py, 'w') as fp:
+                    if with_dependency_links_in_setup_py:
+                        dependency_links = [os.path.join(temp_dir, 'links')]
+                    else:
+                        dependency_links = []
+                    fp.write(DALS(
+                        '''
+                        from setuptools import installer, setup
+                        if {use_legacy_installer}:
+                            installer.fetch_build_egg = installer._legacy_fetch_build_egg
+                        setup(setup_requires='python-xlib==42',
+                        dependency_links={dependency_links!r})
+                        ''').format(use_legacy_installer=use_legacy_installer,  # noqa
+                                    dependency_links=dependency_links))
+                with open(test_setup_cfg, 'w') as fp:
+                    fp.write(DALS(
+                        '''
+                        [easy_install]
+                        index_url = {index_url}
+                        find_links = {find_links}
+                        ''').format(index_url=os.path.join(temp_dir, 'index'),
+                                    find_links=temp_dir))
+                run_setup(test_setup_py, [str('--version')])
+
+    def test_setup_requires_with_transitive_extra_dependency(
+            self, monkeypatch):
+        # Use case: installing a package with a build dependency on
+        # an already installed `dep[extra]`, which in turn depends
+        # on `extra_dep` (whose is not already installed).
+        with contexts.save_pkg_resources_state():
+            with contexts.tempdir() as temp_dir:
+                # Create source distribution for `extra_dep`.
+                make_trivial_sdist(
+                    os.path.join(temp_dir, 'extra_dep-1.0.tar.gz'),
+                    'extra_dep', '1.0')
+                # Create source tree for `dep`.
+                dep_pkg = os.path.join(temp_dir, 'dep')
+                os.mkdir(dep_pkg)
+                build_files({
+                    'setup.py':
+                    DALS("""
+                          import setuptools
+                          setuptools.setup(
+                              name='dep', version='2.0',
+                              extras_require={'extra': ['extra_dep']},
+                          )
+                         """),
+                    'setup.cfg': '',
+                }, prefix=dep_pkg)
+                # "Install" dep.
+                run_setup(
+                    os.path.join(dep_pkg, 'setup.py'), [str('dist_info')])
+                working_set.add_entry(dep_pkg)
+                # Create source tree for test package.
+                test_pkg = os.path.join(temp_dir, 'test_pkg')
+                test_setup_py = os.path.join(test_pkg, 'setup.py')
+                os.mkdir(test_pkg)
+                with open(test_setup_py, 'w') as fp:
+                    fp.write(DALS(
+                        '''
+                        from setuptools import installer, setup
+                        setup(setup_requires='dep[extra]')
+                        '''))
+                # Check...
+                monkeypatch.setenv(str('PIP_FIND_LINKS'), str(temp_dir))
+                monkeypatch.setenv(str('PIP_NO_INDEX'), str('1'))
+                monkeypatch.setenv(str('PIP_RETRIES'), str('0'))
+                monkeypatch.setenv(str('PIP_TIMEOUT'), str('0'))
+                run_setup(test_setup_py, [str('--version')])
+
 
 def make_trivial_sdist(dist_path, distname, version):
     """
@@ -647,7 +855,9 @@ def make_trivial_sdist(dist_path, distname, version):
                  name=%r,
                  version=%r
              )
-         """ % (distname, version)))])
+         """ % (distname, version))),
+        ('setup.cfg', ''),
+    ])
 
 
 def make_nspkg_sdist(dist_path, distname, version):
@@ -683,12 +893,32 @@ def make_nspkg_sdist(dist_path, distname, version):
     make_sdist(dist_path, files)
 
 
+def make_python_requires_sdist(dist_path, distname, version, python_requires):
+    make_sdist(dist_path, [
+        (
+            'setup.py',
+            DALS("""\
+                import setuptools
+                setuptools.setup(
+                  name={name!r},
+                  version={version!r},
+                  python_requires={python_requires!r},
+                )
+                """).format(
+                name=distname, version=version,
+                python_requires=python_requires)),
+        ('setup.cfg', ''),
+    ])
+
+
 def make_sdist(dist_path, files):
     """
     Create a simple sdist tarball at dist_path, containing the files
     listed in ``files`` as ``(filename, content)`` tuples.
     """
 
+    # Distributions with only one file don't play well with pip.
+    assert len(files) > 1
     with tarfile.open(dist_path, 'w:gz') as dist:
         for filename, content in files:
             file_bytes = io.BytesIO(content.encode('utf-8'))
@@ -721,8 +951,8 @@ def create_setup_requires_package(path, distname='foobar', version='0.1',
     test_pkg = os.path.join(path, 'test_pkg')
     os.mkdir(test_pkg)
 
+    # setup.cfg
     if use_setup_cfg:
-        test_setup_cfg = os.path.join(test_pkg, 'setup.cfg')
         options = []
         metadata = []
         for name in use_setup_cfg:
@@ -734,27 +964,29 @@ def create_setup_requires_package(path, distname='foobar', version='0.1',
             if isinstance(value, (tuple, list)):
                 value = ';'.join(value)
             section.append('%s: %s' % (name, value))
-        with open(test_setup_cfg, 'w') as f:
-            f.write(DALS(
-                """
-                [metadata]
-                {metadata}
-                [options]
-                {options}
-                """
-            ).format(
-                options='\n'.join(options),
-                metadata='\n'.join(metadata),
-            ))
-
-    test_setup_py = os.path.join(test_pkg, 'setup.py')
+        test_setup_cfg_contents = DALS(
+            """
+            [metadata]
+            {metadata}
+            [options]
+            {options}
+            """
+        ).format(
+            options='\n'.join(options),
+            metadata='\n'.join(metadata),
+        )
+    else:
+        test_setup_cfg_contents = ''
+    with open(os.path.join(test_pkg, 'setup.cfg'), 'w') as f:
+        f.write(test_setup_cfg_contents)
 
+    # setup.py
     if setup_py_template is None:
         setup_py_template = DALS("""\
             import setuptools
             setuptools.setup(**%r)
         """)
-    with open(test_setup_py, 'w') as f:
+    with open(os.path.join(test_pkg, 'setup.py'), 'w') as f:
         f.write(setup_py_template % test_setup_attrs)
 
     foobar_path = os.path.join(path, '%s-%s.tar.gz' % (distname, version))
diff --git a/setuptools/tests/test_egg_info.py b/setuptools/tests/test_egg_info.py
index 316eb2ed..109f9135 100644
--- a/setuptools/tests/test_egg_info.py
+++ b/setuptools/tests/test_egg_info.py
@@ -524,28 +524,28 @@ class TestEggInfo:
                               [metadata]
                               license_file = LICENSE
                               """),
-            'LICENSE': DALS("Test license")
-        }, True), # with license
+            'LICENSE': "Test license"
+        }, True),  # with license
         ({
             'setup.cfg': DALS("""
                               [metadata]
                               license_file = INVALID_LICENSE
                               """),
-            'LICENSE': DALS("Test license")
-        }, False), # with an invalid license
+            'LICENSE': "Test license"
+        }, False),  # with an invalid license
         ({
             'setup.cfg': DALS("""
                               """),
-            'LICENSE': DALS("Test license")
-        }, False), # no license_file attribute
+            'LICENSE': "Test license"
+        }, False),  # no license_file attribute
         ({
             'setup.cfg': DALS("""
                               [metadata]
                               license_file = LICENSE
                               """),
-            'MANIFEST.in': DALS("exclude LICENSE"),
-            'LICENSE': DALS("Test license")
-        }, False) # license file is manually excluded
+            'MANIFEST.in': "exclude LICENSE",
+            'LICENSE': "Test license"
+        }, False)  # license file is manually excluded
     ])
     def test_setup_cfg_license_file(
             self, tmpdir_cwd, env, files, license_in_sources):
@@ -565,7 +565,211 @@ class TestEggInfo:
             assert 'LICENSE' in sources_text
         else:
             assert 'LICENSE' not in sources_text
-            assert 'INVALID_LICENSE' not in sources_text # for invalid license test
+            # for invalid license test
+            assert 'INVALID_LICENSE' not in sources_text
+
+    @pytest.mark.parametrize("files, incl_licenses, excl_licenses", [
+        ({
+            'setup.cfg': DALS("""
+                              [metadata]
+                              license_files =
+                                  LICENSE-ABC
+                                  LICENSE-XYZ
+                              """),
+            'LICENSE-ABC': "ABC license",
+            'LICENSE-XYZ': "XYZ license"
+        }, ['LICENSE-ABC', 'LICENSE-XYZ'], []),  # with licenses
+        ({
+            'setup.cfg': DALS("""
+                              [metadata]
+                              license_files = LICENSE-ABC, LICENSE-XYZ
+                              """),
+            'LICENSE-ABC': "ABC license",
+            'LICENSE-XYZ': "XYZ license"
+        }, ['LICENSE-ABC', 'LICENSE-XYZ'], []),  # with commas
+        ({
+            'setup.cfg': DALS("""
+                              [metadata]
+                              license_files =
+                                  LICENSE-ABC
+                              """),
+            'LICENSE-ABC': "ABC license",
+            'LICENSE-XYZ': "XYZ license"
+        }, ['LICENSE-ABC'], ['LICENSE-XYZ']),  # with one license
+        ({
+            'setup.cfg': DALS("""
+                              [metadata]
+                              license_files =
+                              """),
+            'LICENSE-ABC': "ABC license",
+            'LICENSE-XYZ': "XYZ license"
+        }, [], ['LICENSE-ABC', 'LICENSE-XYZ']),  # empty
+        ({
+            'setup.cfg': DALS("""
+                              [metadata]
+                              license_files = LICENSE-XYZ
+                              """),
+            'LICENSE-ABC': "ABC license",
+            'LICENSE-XYZ': "XYZ license"
+        }, ['LICENSE-XYZ'], ['LICENSE-ABC']),  # on same line
+        ({
+            'setup.cfg': DALS("""
+                              [metadata]
+                              license_files =
+                                  LICENSE-ABC
+                                  INVALID_LICENSE
+                              """),
+            'LICENSE-ABC': "Test license"
+        }, ['LICENSE-ABC'], ['INVALID_LICENSE']),  # with an invalid license
+        ({
+            'setup.cfg': DALS("""
+                              """),
+            'LICENSE': "Test license"
+        }, [], ['LICENSE']),  # no license_files attribute
+        ({
+            'setup.cfg': DALS("""
+                              [metadata]
+                              license_files = LICENSE
+                              """),
+            'MANIFEST.in': "exclude LICENSE",
+            'LICENSE': "Test license"
+        }, [], ['LICENSE']),  # license file is manually excluded
+        ({
+            'setup.cfg': DALS("""
+                              [metadata]
+                              license_files =
+                                  LICENSE-ABC
+                                  LICENSE-XYZ
+                              """),
+            'MANIFEST.in': "exclude LICENSE-XYZ",
+            'LICENSE-ABC': "ABC license",
+            'LICENSE-XYZ': "XYZ license"
+        }, ['LICENSE-ABC'], ['LICENSE-XYZ'])  # subset is manually excluded
+    ])
+    def test_setup_cfg_license_files(
+            self, tmpdir_cwd, env, files, incl_licenses, excl_licenses):
+        self._create_project()
+        build_files(files)
+
+        environment.run_setup_py(
+            cmd=['egg_info'],
+            pypath=os.pathsep.join([env.paths['lib'], str(tmpdir_cwd)])
+        )
+        egg_info_dir = os.path.join('.', 'foo.egg-info')
+
+        with open(os.path.join(egg_info_dir, 'SOURCES.txt')) as sources_file:
+            sources_lines = list(line.strip() for line in sources_file)
+
+        for lf in incl_licenses:
+            assert sources_lines.count(lf) == 1
+
+        for lf in excl_licenses:
+            assert sources_lines.count(lf) == 0
+
+    @pytest.mark.parametrize("files, incl_licenses, excl_licenses", [
+        ({
+            'setup.cfg': DALS("""
+                              [metadata]
+                              license_file =
+                              license_files =
+                              """),
+            'LICENSE-ABC': "ABC license",
+            'LICENSE-XYZ': "XYZ license"
+        }, [], ['LICENSE-ABC', 'LICENSE-XYZ']),  # both empty
+        ({
+            'setup.cfg': DALS("""
+                              [metadata]
+                              license_file =
+                                  LICENSE-ABC
+                                  LICENSE-XYZ
+                              """),
+            'LICENSE-ABC': "ABC license",
+            'LICENSE-XYZ': "XYZ license"
+            # license_file is still singular
+        }, [], ['LICENSE-ABC', 'LICENSE-XYZ']),
+        ({
+            'setup.cfg': DALS("""
+                              [metadata]
+                              license_file = LICENSE-ABC
+                              license_files =
+                                  LICENSE-XYZ
+                                  LICENSE-PQR
+                              """),
+            'LICENSE-ABC': "ABC license",
+            'LICENSE-PQR': "PQR license",
+            'LICENSE-XYZ': "XYZ license"
+        }, ['LICENSE-ABC', 'LICENSE-PQR', 'LICENSE-XYZ'], []),  # combined
+        ({
+            'setup.cfg': DALS("""
+                              [metadata]
+                              license_file = LICENSE-ABC
+                              license_files =
+                                  LICENSE-ABC
+                                  LICENSE-XYZ
+                                  LICENSE-PQR
+                              """),
+            'LICENSE-ABC': "ABC license",
+            'LICENSE-PQR': "PQR license",
+            'LICENSE-XYZ': "XYZ license"
+            # duplicate license
+        }, ['LICENSE-ABC', 'LICENSE-PQR', 'LICENSE-XYZ'], []),
+        ({
+            'setup.cfg': DALS("""
+                              [metadata]
+                              license_file = LICENSE-ABC
+                              license_files =
+                                  LICENSE-XYZ
+                              """),
+            'LICENSE-ABC': "ABC license",
+            'LICENSE-PQR': "PQR license",
+            'LICENSE-XYZ': "XYZ license"
+            # combined subset
+        }, ['LICENSE-ABC', 'LICENSE-XYZ'], ['LICENSE-PQR']),
+        ({
+            'setup.cfg': DALS("""
+                              [metadata]
+                              license_file = LICENSE-ABC
+                              license_files =
+                                  LICENSE-XYZ
+                                  LICENSE-PQR
+                              """),
+            'LICENSE-PQR': "Test license"
+            # with invalid licenses
+        }, ['LICENSE-PQR'], ['LICENSE-ABC', 'LICENSE-XYZ']),
+        ({
+            'setup.cfg': DALS("""
+                              [metadata]
+                              license_file = LICENSE-ABC
+                              license_files =
+                                LICENSE-PQR
+                                LICENSE-XYZ
+                              """),
+            'MANIFEST.in': "exclude LICENSE-ABC\nexclude LICENSE-PQR",
+            'LICENSE-ABC': "ABC license",
+            'LICENSE-PQR': "PQR license",
+            'LICENSE-XYZ': "XYZ license"
+            # manually excluded
+        }, ['LICENSE-XYZ'], ['LICENSE-ABC', 'LICENSE-PQR'])
+    ])
+    def test_setup_cfg_license_file_license_files(
+            self, tmpdir_cwd, env, files, incl_licenses, excl_licenses):
+        self._create_project()
+        build_files(files)
+
+        environment.run_setup_py(
+            cmd=['egg_info'],
+            pypath=os.pathsep.join([env.paths['lib'], str(tmpdir_cwd)])
+        )
+        egg_info_dir = os.path.join('.', 'foo.egg-info')
+
+        with open(os.path.join(egg_info_dir, 'SOURCES.txt')) as sources_file:
+            sources_lines = list(line.strip() for line in sources_file)
+
+        for lf in incl_licenses:
+            assert sources_lines.count(lf) == 1
+
+        for lf in excl_licenses:
+            assert sources_lines.count(lf) == 0
 
     def test_long_description_content_type(self, tmpdir_cwd, env):
         # Test that specifying a `long_description_content_type` keyword arg to
diff --git a/setuptools/tests/test_glibc.py b/setuptools/tests/test_glibc.py
deleted file mode 100644
index 795fdc56..00000000
--- a/setuptools/tests/test_glibc.py
+++ /dev/null
@@ -1,52 +0,0 @@
-import warnings
-
-import pytest
-
-from setuptools.glibc import check_glibc_version
-
-__metaclass__ = type
-
-
-@pytest.fixture(params=[
-    "2.20",
-    # used by "linaro glibc", see gh-3588
-    "2.20-2014.11",
-    # weird possibilities that I just made up
-    "2.20+dev",
-    "2.20-custom",
-    "2.20.1",
-    ])
-def two_twenty(request):
-    return request.param
-
-
-@pytest.fixture(params=["asdf", "", "foo.bar"])
-def bad_string(request):
-    return request.param
-
-
-class TestGlibc:
-    def test_manylinux1_check_glibc_version(self, two_twenty):
-        """
-        Test that the check_glibc_version function is robust against weird
-        glibc version strings.
-        """
-        assert check_glibc_version(two_twenty, 2, 15)
-        assert check_glibc_version(two_twenty, 2, 20)
-        assert not check_glibc_version(two_twenty, 2, 21)
-        assert not check_glibc_version(two_twenty, 3, 15)
-        assert not check_glibc_version(two_twenty, 1, 15)
-
-    def test_bad_versions(self, bad_string):
-        """
-        For unparseable strings, warn and return False
-        """
-        with warnings.catch_warnings(record=True) as ws:
-            warnings.filterwarnings("always")
-            assert not check_glibc_version(bad_string, 2, 5)
-            for w in ws:
-                if "Expected glibc version with" in str(w.message):
-                    break
-            else:
-                # Didn't find the warning we were expecting
-                assert False
diff --git a/setuptools/tests/test_integration.py b/setuptools/tests/test_integration.py
index 1c0b2b18..f1a27f8b 100644
--- a/setuptools/tests/test_integration.py
+++ b/setuptools/tests/test_integration.py
@@ -64,7 +64,7 @@ def install_context(request, tmpdir, monkeypatch):
     monkeypatch.setattr('site.USER_BASE', user_base.strpath)
     monkeypatch.setattr('site.USER_SITE', user_site.strpath)
     monkeypatch.setattr('sys.path', sys.path + [install_dir.strpath])
-    monkeypatch.setenv('PYTHONPATH', os.path.pathsep.join(sys.path))
+    monkeypatch.setenv(str('PYTHONPATH'), str(os.path.pathsep.join(sys.path)))
 
     # Set up the command for performing the installation.
     dist = Distribution()
diff --git a/setuptools/tests/test_pep425tags.py b/setuptools/tests/test_pep425tags.py
deleted file mode 100644
index 30afdec7..00000000
--- a/setuptools/tests/test_pep425tags.py
+++ /dev/null
@@ -1,170 +0,0 @@
-import sys
-
-import pytest
-from mock import patch
-
-from setuptools import pep425tags
-
-__metaclass__ = type
-
-
-class TestPEP425Tags:
-
-    def mock_get_config_var(self, **kwd):
-        """
-        Patch sysconfig.get_config_var for arbitrary keys.
-        """
-        get_config_var = pep425tags.sysconfig.get_config_var
-
-        def _mock_get_config_var(var):
-            if var in kwd:
-                return kwd[var]
-            return get_config_var(var)
-        return _mock_get_config_var
-
-    def abi_tag_unicode(self, flags, config_vars):
-        """
-        Used to test ABI tags, verify correct use of the `u` flag
-        """
-        config_vars.update({'SOABI': None})
-        base = pep425tags.get_abbr_impl() + pep425tags.get_impl_ver()
-
-        if sys.version_info < (3, 3):
-            config_vars.update({'Py_UNICODE_SIZE': 2})
-            mock_gcf = self.mock_get_config_var(**config_vars)
-            with patch(
-                    'setuptools.pep425tags.sysconfig.get_config_var',
-                    mock_gcf):
-                abi_tag = pep425tags.get_abi_tag()
-                assert abi_tag == base + flags
-
-            config_vars.update({'Py_UNICODE_SIZE': 4})
-            mock_gcf = self.mock_get_config_var(**config_vars)
-            with patch('setuptools.pep425tags.sysconfig.get_config_var',
-                       mock_gcf):
-                abi_tag = pep425tags.get_abi_tag()
-                assert abi_tag == base + flags + 'u'
-
-        else:
-            # On Python >= 3.3, UCS-4 is essentially permanently enabled, and
-            # Py_UNICODE_SIZE is None. SOABI on these builds does not include
-            # the 'u' so manual SOABI detection should not do so either.
-            config_vars.update({'Py_UNICODE_SIZE': None})
-            mock_gcf = self.mock_get_config_var(**config_vars)
-            with patch('setuptools.pep425tags.sysconfig.get_config_var',
-                       mock_gcf):
-                abi_tag = pep425tags.get_abi_tag()
-                assert abi_tag == base + flags
-
-    def test_broken_sysconfig(self):
-        """
-        Test that pep425tags still works when sysconfig is broken.
-        Can be a problem on Python 2.7
-        Issue #1074.
-        """
-        def raises_ioerror(var):
-            raise IOError("I have the wrong path!")
-
-        with patch('setuptools.pep425tags.sysconfig.get_config_var',
-                   raises_ioerror):
-            with pytest.warns(RuntimeWarning):
-                assert len(pep425tags.get_supported())
-
-    def test_no_hyphen_tag(self):
-        """
-        Test that no tag contains a hyphen.
-        """
-        mock_gcf = self.mock_get_config_var(SOABI='cpython-35m-darwin')
-
-        with patch('setuptools.pep425tags.sysconfig.get_config_var',
-                   mock_gcf):
-            supported = pep425tags.get_supported()
-
-        for (py, abi, plat) in supported:
-            assert '-' not in py
-            assert '-' not in abi
-            assert '-' not in plat
-
-    def test_manual_abi_noflags(self):
-        """
-        Test that no flags are set on a non-PyDebug, non-Pymalloc ABI tag.
-        """
-        self.abi_tag_unicode('', {'Py_DEBUG': False, 'WITH_PYMALLOC': False})
-
-    def test_manual_abi_d_flag(self):
-        """
-        Test that the `d` flag is set on a PyDebug, non-Pymalloc ABI tag.
-        """
-        self.abi_tag_unicode('d', {'Py_DEBUG': True, 'WITH_PYMALLOC': False})
-
-    def test_manual_abi_m_flag(self):
-        """
-        Test that the `m` flag is set on a non-PyDebug, Pymalloc ABI tag.
-        """
-        self.abi_tag_unicode('m', {'Py_DEBUG': False, 'WITH_PYMALLOC': True})
-
-    def test_manual_abi_dm_flags(self):
-        """
-        Test that the `dm` flags are set on a PyDebug, Pymalloc ABI tag.
-        """
-        self.abi_tag_unicode('dm', {'Py_DEBUG': True, 'WITH_PYMALLOC': True})
-
-
-class TestManylinux1Tags:
-
-    @patch('setuptools.pep425tags.get_platform', lambda: 'linux_x86_64')
-    @patch('setuptools.glibc.have_compatible_glibc',
-           lambda major, minor: True)
-    def test_manylinux1_compatible_on_linux_x86_64(self):
-        """
-        Test that manylinux1 is enabled on linux_x86_64
-        """
-        assert pep425tags.is_manylinux1_compatible()
-
-    @patch('setuptools.pep425tags.get_platform', lambda: 'linux_i686')
-    @patch('setuptools.glibc.have_compatible_glibc',
-           lambda major, minor: True)
-    def test_manylinux1_compatible_on_linux_i686(self):
-        """
-        Test that manylinux1 is enabled on linux_i686
-        """
-        assert pep425tags.is_manylinux1_compatible()
-
-    @patch('setuptools.pep425tags.get_platform', lambda: 'linux_x86_64')
-    @patch('setuptools.glibc.have_compatible_glibc',
-           lambda major, minor: False)
-    def test_manylinux1_2(self):
-        """
-        Test that manylinux1 is disabled with incompatible glibc
-        """
-        assert not pep425tags.is_manylinux1_compatible()
-
-    @patch('setuptools.pep425tags.get_platform', lambda: 'arm6vl')
-    @patch('setuptools.glibc.have_compatible_glibc',
-           lambda major, minor: True)
-    def test_manylinux1_3(self):
-        """
-        Test that manylinux1 is disabled on arm6vl
-        """
-        assert not pep425tags.is_manylinux1_compatible()
-
-    @patch('setuptools.pep425tags.get_platform', lambda: 'linux_x86_64')
-    @patch('setuptools.glibc.have_compatible_glibc',
-           lambda major, minor: True)
-    @patch('sys.platform', 'linux2')
-    def test_manylinux1_tag_is_first(self):
-        """
-        Test that the more specific tag manylinux1 comes first.
-        """
-        groups = {}
-        for pyimpl, abi, arch in pep425tags.get_supported():
-            groups.setdefault((pyimpl, abi), []).append(arch)
-
-        for arches in groups.values():
-            if arches == ['any']:
-                continue
-            # Expect the most specific arch first:
-            if len(arches) == 3:
-                assert arches == ['manylinux1_x86_64', 'linux_x86_64', 'any']
-            else:
-                assert arches == ['manylinux1_x86_64', 'linux_x86_64']
diff --git a/setuptools/tests/test_sdist.py b/setuptools/tests/test_sdist.py
index d2c4e0cf..0bea53df 100644
--- a/setuptools/tests/test_sdist.py
+++ b/setuptools/tests/test_sdist.py
@@ -1,8 +1,9 @@
 # -*- coding: utf-8 -*-
 """sdist tests"""
 
+from __future__ import print_function, unicode_literals
+
 import os
-import shutil
 import sys
 import tempfile
 import unicodedata
@@ -50,7 +51,7 @@ def quiet():
 
 # Convert to POSIX path
 def posix(path):
-    if six.PY3 and not isinstance(path, str):
+    if not six.PY2 and not isinstance(path, str):
         return path.replace(os.sep.encode('ascii'), b'/')
     else:
         return path.replace(os.sep, '/')
@@ -89,30 +90,28 @@ fail_on_latin1_encoded_filenames = pytest.mark.xfail(
 )
 
 
+def touch(path):
+    path.write_text('', encoding='utf-8')
+
+
 class TestSdistTest:
-    def setup_method(self, method):
-        self.temp_dir = tempfile.mkdtemp()
-        with open(os.path.join(self.temp_dir, 'setup.py'), 'w') as f:
-            f.write(SETUP_PY)
+    @pytest.fixture(autouse=True)
+    def source_dir(self, tmpdir):
+        (tmpdir / 'setup.py').write_text(SETUP_PY, encoding='utf-8')
 
         # Set up the rest of the test package
-        test_pkg = os.path.join(self.temp_dir, 'sdist_test')
-        os.mkdir(test_pkg)
-        data_folder = os.path.join(self.temp_dir, "d")
-        os.mkdir(data_folder)
+        test_pkg = tmpdir / 'sdist_test'
+        test_pkg.mkdir()
+        data_folder = tmpdir / 'd'
+        data_folder.mkdir()
         # *.rst was not included in package_data, so c.rst should not be
         # automatically added to the manifest when not under version control
-        for fname in ['__init__.py', 'a.txt', 'b.txt', 'c.rst',
-                      os.path.join(data_folder, "e.dat")]:
-            # Just touch the files; their contents are irrelevant
-            open(os.path.join(test_pkg, fname), 'w').close()
-
-        self.old_cwd = os.getcwd()
-        os.chdir(self.temp_dir)
+        for fname in ['__init__.py', 'a.txt', 'b.txt', 'c.rst']:
+            touch(test_pkg / fname)
+        touch(data_folder / 'e.dat')
 
-    def teardown_method(self, method):
-        os.chdir(self.old_cwd)
-        shutil.rmtree(self.temp_dir)
+        with tmpdir.as_cwd():
+            yield
 
     def test_package_data_in_sdist(self):
         """Regression test for pull request #4: ensures that files listed in
@@ -175,14 +174,14 @@ class TestSdistTest:
         manifest = cmd.filelist.files
         assert 'setup.py' not in manifest
 
-    def test_defaults_case_sensitivity(self):
+    def test_defaults_case_sensitivity(self, tmpdir):
         """
         Make sure default files (README.*, etc.) are added in a case-sensitive
         way to avoid problems with packages built on Windows.
         """
 
-        open(os.path.join(self.temp_dir, 'readme.rst'), 'w').close()
-        open(os.path.join(self.temp_dir, 'SETUP.cfg'), 'w').close()
+        touch(tmpdir / 'readme.rst')
+        touch(tmpdir / 'SETUP.cfg')
 
         dist = Distribution(SETUP_ATTRS)
         # the extension deliberately capitalized for this test
@@ -230,10 +229,6 @@ class TestSdistTest:
         u_contents = contents.decode('UTF-8')
 
         # The manifest should contain the UTF-8 filename
-        if six.PY2:
-            fs_enc = sys.getfilesystemencoding()
-            filename = filename.decode(fs_enc)
-
         assert posix(filename) in u_contents
 
     @py3_only
@@ -334,7 +329,7 @@ class TestSdistTest:
             cmd.read_manifest()
 
         # The filelist should contain the UTF-8 filename
-        if six.PY3:
+        if not six.PY2:
             filename = filename.decode('utf-8')
         assert filename in cmd.filelist.files
 
@@ -374,7 +369,7 @@ class TestSdistTest:
     @fail_on_latin1_encoded_filenames
     def test_sdist_with_utf8_encoded_filename(self):
         # Test for #303.
-        dist = Distribution(SETUP_ATTRS)
+        dist = Distribution(self.make_strings(SETUP_ATTRS))
         dist.script_name = 'setup.py'
         cmd = sdist(dist)
         cmd.ensure_finalized()
@@ -388,7 +383,7 @@ class TestSdistTest:
         if sys.platform == 'darwin':
             filename = decompose(filename)
 
-        if six.PY3:
+        if not six.PY2:
             fs_enc = sys.getfilesystemencoding()
 
             if sys.platform == 'win32':
@@ -405,10 +400,19 @@ class TestSdistTest:
         else:
             assert filename in cmd.filelist.files
 
+    @classmethod
+    def make_strings(cls, item):
+        if isinstance(item, dict):
+            return {
+                key: cls.make_strings(value) for key, value in item.items()}
+        if isinstance(item, list):
+            return list(map(cls.make_strings, item))
+        return str(item)
+
     @fail_on_latin1_encoded_filenames
     def test_sdist_with_latin1_encoded_filename(self):
         # Test for #303.
-        dist = Distribution(SETUP_ATTRS)
+        dist = Distribution(self.make_strings(SETUP_ATTRS))
         dist.script_name = 'setup.py'
         cmd = sdist(dist)
         cmd.ensure_finalized()
@@ -421,7 +425,19 @@ class TestSdistTest:
         with quiet():
             cmd.run()
 
-        if six.PY3:
+        if six.PY2:
+            # Under Python 2 there seems to be no decoded string in the
+            # filelist.  However, due to decode and encoding of the
+            # file name to get utf-8 Manifest the latin1 maybe excluded
+            try:
+                # fs_enc should match how one is expect the decoding to
+                # be proformed for the manifest output.
+                fs_enc = sys.getfilesystemencoding()
+                filename.decode(fs_enc)
+                assert filename in cmd.filelist.files
+            except UnicodeDecodeError:
+                filename not in cmd.filelist.files
+        else:
             # not all windows systems have a default FS encoding of cp1252
             if sys.platform == 'win32':
                 # Latin-1 is similar to Windows-1252 however
@@ -436,18 +452,36 @@ class TestSdistTest:
                 # The Latin-1 filename should have been skipped
                 filename = filename.decode('latin-1')
                 filename not in cmd.filelist.files
-        else:
-            # Under Python 2 there seems to be no decoded string in the
-            # filelist.  However, due to decode and encoding of the
-            # file name to get utf-8 Manifest the latin1 maybe excluded
-            try:
-                # fs_enc should match how one is expect the decoding to
-                # be proformed for the manifest output.
-                fs_enc = sys.getfilesystemencoding()
-                filename.decode(fs_enc)
-                assert filename in cmd.filelist.files
-            except UnicodeDecodeError:
-                filename not in cmd.filelist.files
+
+    def test_pyproject_toml_in_sdist(self, tmpdir):
+        """
+        Check if pyproject.toml is included in source distribution if present
+        """
+        touch(tmpdir / 'pyproject.toml')
+        dist = Distribution(SETUP_ATTRS)
+        dist.script_name = 'setup.py'
+        cmd = sdist(dist)
+        cmd.ensure_finalized()
+        with quiet():
+            cmd.run()
+        manifest = cmd.filelist.files
+        assert 'pyproject.toml' in manifest
+
+    def test_pyproject_toml_excluded(self, tmpdir):
+        """
+        Check that pyproject.toml can excluded even if present
+        """
+        touch(tmpdir / 'pyproject.toml')
+        with open('MANIFEST.in', 'w') as mts:
+            print('exclude pyproject.toml', file=mts)
+        dist = Distribution(SETUP_ATTRS)
+        dist.script_name = 'setup.py'
+        cmd = sdist(dist)
+        cmd.ensure_finalized()
+        with quiet():
+            cmd.run()
+        manifest = cmd.filelist.files
+        assert 'pyproject.toml' not in manifest
 
 
 def test_default_revctrl():
diff --git a/setuptools/tests/test_setopt.py b/setuptools/tests/test_setopt.py
index 3fb04fb4..1b038954 100644
--- a/setuptools/tests/test_setopt.py
+++ b/setuptools/tests/test_setopt.py
@@ -15,7 +15,7 @@ class TestEdit:
     def parse_config(filename):
         parser = configparser.ConfigParser()
         with io.open(filename, encoding='utf-8') as reader:
-            (parser.read_file if six.PY3 else parser.readfp)(reader)
+            (parser.readfp if six.PY2 else parser.read_file)(reader)
         return parser
 
     @staticmethod
diff --git a/setuptools/tests/test_setuptools.py b/setuptools/tests/test_setuptools.py
index 5896a69a..0da19b0e 100644
--- a/setuptools/tests/test_setuptools.py
+++ b/setuptools/tests/test_setuptools.py
@@ -223,10 +223,10 @@ class TestFeatures:
                                py_modules=['bar_et'], remove=['bar.ext'],
                                ),
                 'baz': Feature(
-                        "baz", optional=False, packages=['pkg.baz'],
-                        scripts=['scripts/baz_it'],
-                        libraries=[('libfoo', 'foo/foofoo.c')]
-                       ),
+                    "baz", optional=False, packages=['pkg.baz'],
+                    scripts=['scripts/baz_it'],
+                    libraries=[('libfoo', 'foo/foofoo.c')]
+                ),
                 'dwim': Feature("DWIM", available=False, remove='bazish'),
             },
             script_args=['--without-bar', 'install'],
diff --git a/setuptools/tests/test_test.py b/setuptools/tests/test_test.py
index 6242a018..8ee70a7e 100644
--- a/setuptools/tests/test_test.py
+++ b/setuptools/tests/test_test.py
@@ -12,7 +12,7 @@ from setuptools.command.test import test
 from setuptools.dist import Distribution
 
 from .textwrap import DALS
-from . import contexts
+
 
 SETUP_PY = DALS("""
     from setuptools import setup
diff --git a/setuptools/tests/test_virtualenv.py b/setuptools/tests/test_virtualenv.py
index 74a1284c..b009fbd6 100644
--- a/setuptools/tests/test_virtualenv.py
+++ b/setuptools/tests/test_virtualenv.py
@@ -8,8 +8,6 @@ from pytest_fixture_config import yield_requires_config
 
 import pytest_virtualenv
 
-from setuptools.extern import six
-
 from .textwrap import DALS
 from .test_easy_install import make_nspkg_sdist
 
@@ -64,7 +62,7 @@ def _get_pip_versions():
             from urllib.request import urlopen
             from urllib.error import URLError
         except ImportError:
-            from urllib2 import urlopen, URLError # Python 2.7 compat
+            from urllib2 import urlopen, URLError  # Python 2.7 compat
 
         try:
             urlopen('https://pypi.org', timeout=1)
@@ -77,12 +75,9 @@ def _get_pip_versions():
         'pip==10.0.1',
         'pip==18.1',
         'pip==19.0.1',
+        'https://github.com/pypa/pip/archive/master.zip',
     ]
 
-    # Pip's master dropped support for 3.4.
-    if not six.PY34:
-        network_versions.append('https://github.com/pypa/pip/archive/master.zip')
-
     versions = [None] + [
         pytest.param(v, **({} if network else {'marks': pytest.mark.skip}))
         for v in network_versions
@@ -121,14 +116,12 @@ def test_pip_upgrade_from_source(pip_version, virtualenv):
     virtualenv.run('pip install --no-cache-dir --upgrade ' + sdist)
 
 
-def test_test_command_install_requirements(bare_virtualenv, tmpdir):
+def _check_test_command_install_requirements(virtualenv, tmpdir):
     """
     Check the test command will install all required dependencies.
     """
-    bare_virtualenv.run(' && '.join((
-        'cd {source}',
-        'python setup.py develop',
-    )).format(source=SOURCE_DIR))
+    # Install setuptools.
+    virtualenv.run('python setup.py develop', cd=SOURCE_DIR)
 
     def sdist(distname, version):
         dist_path = tmpdir.join('%s-%s.tar.gz' % (distname, version))
@@ -179,13 +172,25 @@ def test_test_command_install_requirements(bare_virtualenv, tmpdir):
             open('success', 'w').close()
             '''))
     # Run test command for test package.
-    bare_virtualenv.run(' && '.join((
+    virtualenv.run(' && '.join((
         'cd {tmpdir}',
         'python setup.py test -s test',
     )).format(tmpdir=tmpdir))
     assert tmpdir.join('success').check()
 
 
+def test_test_command_install_requirements(virtualenv, tmpdir):
+    # Ensure pip/wheel packages are installed.
+    virtualenv.run(
+        "python -c \"__import__('pkg_resources').require(['pip', 'wheel'])\"")
+    _check_test_command_install_requirements(virtualenv, tmpdir)
+
+
+def test_test_command_install_requirements_when_using_easy_install(
+        bare_virtualenv, tmpdir):
+    _check_test_command_install_requirements(bare_virtualenv, tmpdir)
+
+
 def test_no_missing_dependencies(bare_virtualenv):
     """
     Quick and dirty test to ensure all external dependencies are vendored.
diff --git a/setuptools/tests/test_wheel.py b/setuptools/tests/test_wheel.py
index d50816c2..f72ccbbf 100644
--- a/setuptools/tests/test_wheel.py
+++ b/setuptools/tests/test_wheel.py
@@ -18,6 +18,7 @@ import pytest
 
 from pkg_resources import Distribution, PathMetadata, PY_MAJOR
 from setuptools.extern.packaging.utils import canonicalize_name
+from setuptools.extern.packaging.tags import parse_tag
 from setuptools.wheel import Wheel
 
 from .contexts import tempdir
@@ -124,11 +125,12 @@ def flatten_tree(tree):
 
 
 def format_install_tree(tree):
-    return {x.format(
-        py_version=PY_MAJOR,
-        platform=get_platform(),
-        shlib_ext=get_config_var('EXT_SUFFIX') or get_config_var('SO'))
-            for x in tree}
+    return {
+        x.format(
+            py_version=PY_MAJOR,
+            platform=get_platform(),
+            shlib_ext=get_config_var('EXT_SUFFIX') or get_config_var('SO'))
+        for x in tree}
 
 
 def _check_wheel_install(filename, install_dir, install_tree_includes,
@@ -454,7 +456,8 @@ WHEEL_INSTALL_TESTS = (
         id='empty_namespace_package',
         file_defs={
             'foobar': {
-                '__init__.py': "__import__('pkg_resources').declare_namespace(__name__)",
+                '__init__.py':
+                    "__import__('pkg_resources').declare_namespace(__name__)",
             },
         },
         setup_kwargs=dict(
@@ -571,3 +574,12 @@ def test_wheel_no_dist_dir():
                 _check_wheel_install(wheel_path, install_dir, None,
                                      project_name,
                                      version, None)
+
+
+def test_wheel_is_compatible(monkeypatch):
+    def sys_tags():
+        for t in parse_tag('cp36-cp36m-manylinux1_x86_64'):
+            yield t
+    monkeypatch.setattr('setuptools.wheel.sys_tags', sys_tags)
+    assert Wheel(
+        'onnxruntime-0.1.2-cp36-cp36m-manylinux1_x86_64.whl').is_compatible()
diff --git a/setuptools/wheel.py b/setuptools/wheel.py
index 22eec05e..ec1106a7 100644
--- a/setuptools/wheel.py
+++ b/setuptools/wheel.py
@@ -12,9 +12,9 @@ import zipfile
 import pkg_resources
 import setuptools
 from pkg_resources import parse_version
+from setuptools.extern.packaging.tags import sys_tags
 from setuptools.extern.packaging.utils import canonicalize_name
 from setuptools.extern.six import PY3
-from setuptools import pep425tags
 from setuptools.command.egg_info import write_requirements
 
 
@@ -77,7 +77,8 @@ class Wheel:
 
     def is_compatible(self):
         '''Is the wheel is compatible with the current platform?'''
-        supported_tags = pep425tags.get_supported()
+        supported_tags = set(
+            (t.interpreter, t.abi, t.platform) for t in sys_tags())
         return next((True for t in self.tags() if t in supported_tags), False)
 
     def egg_name(self):
diff --git a/tests/requirements.txt b/tests/requirements.txt
index 1f70adee..19bf5aef 100644
--- a/tests/requirements.txt
+++ b/tests/requirements.txt
@@ -1,6 +1,6 @@
 mock
-pytest-flake8; python_version!="3.4"
-pytest-flake8<=1.0.0; python_version=="3.4"
+pytest-flake8
+flake8-2020; python_version>="3.6"
 virtualenv>=13.0.0
 pytest-virtualenv>=1.2.7
 pytest>=3.7
@@ -9,3 +9,4 @@ coverage>=4.5.1
 pytest-cov>=2.5.1
 paver; python_version>="3.6"
 futures; python_version=="2.7"
+pip>=19.1 # For proper file:// URLs support.
diff --git a/tools/tox_pip.py b/tools/tox_pip.py
index 1117f996..2d33e9e5 100644
--- a/tools/tox_pip.py
+++ b/tools/tox_pip.py
@@ -1,28 +1,36 @@
 import os
-import shutil
 import subprocess
 import sys
-from glob import glob
 
-VIRTUAL_ENV = os.environ['VIRTUAL_ENV']
-TOX_PIP_DIR = os.path.join(VIRTUAL_ENV, 'pip')
+
+def remove_setuptools():
+    """
+    Remove setuptools from the current environment.
+    """
+    print("Removing setuptools")
+    cmd = [sys.executable, '-m', 'pip', 'uninstall', '-y', 'setuptools']
+    # set cwd to something other than '.' to avoid detecting
+    # '.' as the installed package.
+    subprocess.check_call(cmd, cwd='.tox')
+
+
+def bootstrap():
+    print("Running bootstrap")
+    cmd = [sys.executable, '-m', 'bootstrap']
+    subprocess.check_call(cmd)
 
 
 def pip(args):
-    # First things first, get a recent (stable) version of pip.
-    if not os.path.exists(TOX_PIP_DIR):
-        subprocess.check_call([sys.executable, '-m', 'pip',
-                               '--disable-pip-version-check',
-                               'install', '-t', TOX_PIP_DIR,
-                               'pip'])
-        shutil.rmtree(glob(os.path.join(TOX_PIP_DIR, 'pip-*.dist-info'))[0])
-    # And use that version.
-    for n, a in enumerate(args):
-        if not a.startswith('-'):
-            if a in 'install' and '-e' in args[n:]:
-                args.insert(n + 1, '--no-use-pep517')
-            break
-    subprocess.check_call([sys.executable, os.path.join(TOX_PIP_DIR, 'pip')] + args)
+    # Honor requires-python when installing test suite dependencies
+    if any('-r' in arg for arg in args):
+        os.environ['PIP_IGNORE_REQUIRES_PYTHON'] = '0'
+
+    if '.' in args:
+        remove_setuptools()
+        bootstrap()
+
+    cmd = [sys.executable, '-m', 'pip'] + args
+    subprocess.check_call(cmd)
 
 
 if __name__ == '__main__':
diff --git a/tox.ini b/tox.ini
index 8b34c235..a70dff87 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,23 +1,25 @@
-# Note: Run "python bootstrap.py" before running Tox, to generate metadata.
-#
 # To run Tox against all supported Python interpreters, you can set:
 #
-# export TOXENV='py27,py3{4,5,6},pypy,pypy3'
+# export TOXENV='py3{5,6,7,8},pypy,pypy3'
 
 [tox]
 envlist=python
+minversion = 3.2
+requires =
+	tox-pip-version >= 0.0.6
 
 [helpers]
-# Wrapper for calls to pip that make sure the version being used is a
-# up-to-date, and to prevent the current working directory from being
-# added to `sys.path`.
+# Custom pip behavior
 pip = python {toxinidir}/tools/tox_pip.py
 
 [testenv]
-deps=-rtests/requirements.txt
+deps=-r{toxinidir}/tests/requirements.txt
+pip_version = pip
 install_command = {[helpers]pip} install {opts} {packages}
 list_dependencies_command = {[helpers]pip} freeze --all
-setenv=COVERAGE_FILE={toxworkdir}/.coverage.{envname}
+setenv =
+	COVERAGE_FILE={toxworkdir}/.coverage.{envname}
+	py27: PIP_IGNORE_REQUIRES_PYTHON=true
 # TODO: The passed environment variables came from copying other tox.ini files
 # These should probably be individually annotated to explain what needs them.
 passenv=APPDATA HOMEDRIVE HOMEPATH windir APPVEYOR APPVEYOR_* CI CODECOV_* TRAVIS TRAVIS_* NETWORK_REQUIRED
@@ -45,7 +47,7 @@ commands=codecov -X gcov --file {toxworkdir}/coverage.xml
 deps = -r{toxinidir}/docs/requirements.txt
 skip_install=True
 commands =
-    python {toxinidir}/bootstrap.py
+    python -m bootstrap
     sphinx-build -W -b html -d {envtmpdir}/doctrees docs docs/build/html
     sphinx-build -W -b man -d {envtmpdir}/doctrees docs docs/build/man
 
@@ -55,3 +57,22 @@ source=
 	setuptools
 omit=
 	*/_vendor/*
+
+[testenv:release]
+skip_install = True
+deps =
+	wheel
+	twine[keyring]>=1.13
+	path
+	jaraco.tidelift
+passenv =
+	TWINE_PASSWORD
+	TIDELIFT_TOKEN
+setenv =
+	TWINE_USERNAME = {env:TWINE_USERNAME:__token__}
+commands =
+	python -m bootstrap
+	python -c "import path; path.Path('dist').rmtree_p()"
+	python setup.py release
+	python -m twine upload dist/*
+	python -m jaraco.tidelift.publish-release-notes