Merge branch 'master' into docs/setup.cfg-only

87 files changed, 1686 insertions, 999 deletions

diff --git a/.bumpversion.cfg b/.bumpversion.cfg
index 77143907..4ee92185 100644
--- a/.bumpversion.cfg
+++ b/.bumpversion.cfg
@@ -1,7 +1,6 @@
 [bumpversion]
-current_version = 45.0.0
+current_version = 46.3.1
 commit = True
 tag = True
 
 [bumpversion:file:setup.cfg]
-
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/FUNDING.yml b/.github/FUNDING.yml
new file mode 100644
index 00000000..27de01d0
--- /dev/null
+++ b/.github/FUNDING.yml
@@ -0,0 +1 @@
+tidelift: pypi/setuptools
diff --git a/.github/ISSUE_TEMPLATE/setuptools-warns-about-python-2-incompatibility.md b/.github/ISSUE_TEMPLATE/setuptools-warns-about-python-2-incompatibility.md
new file mode 100644
index 00000000..2f5fe53d
--- /dev/null
+++ b/.github/ISSUE_TEMPLATE/setuptools-warns-about-python-2-incompatibility.md
@@ -0,0 +1,53 @@
+---
+name: Setuptools warns about Python 2 incompatibility
+about: Report the issue where setuptools 45 or later stops working on Python 2
+title: Incompatible install in (summarize your environment)
+labels: Python 2
+assignees: ''
+
+---
+
+<!--
+
+Please DO NOT SUBMIT this template without first investigating the issue and answering the questions below. This template is intended mainly for developers of systems and not for end users. If you are an end user experiencing the warning, please work with your system maintainers (starting with the project you're trying to use) to report the issue.
+
+If you did not intend to use this template, but only meant to file a blank issue, just hit the back button and click "Open a blank issue".
+
+It's by design that Setuptools 45 and later will stop working on Python 2. To ease the transition, Setuptools 45 was released to continue to have Python 2 compatibility, but emit a strenuous warning that it will stop working.
+
+In most cases, using pip 9 or later to install Setuptools from PyPI or any index supporting the Requires-Python metadata will do the right thing and install Setuptools 44.x on Python 2.
+
+If you've come to file an issue, it's probably because some process managed to bypass these protections.
+
+Your first course of action should be to reason about how you managed to get an unsupported version of Setuptools on Python 2. Please complete the sections below and provide any other detail about your environment that will help us help you.
+
+-->
+
+## Prerequisites
+
+<!-- These are the recommended workarounds for the issue. Please
+try them first. -->
+
+- [ ] Python 2 is required for this application.
+- [ ] I maintain the software that installs Setuptools (if not, please contact that project).
+- [ ] Setuptools installed with pip 9 or later.
+- [ ] Pinning Setuptools to `setuptools<45` in the environment was unsuccessful.
+
+## Environment Details
+
+- Operating System and version:
+- Python version:
+- Python installed how:
+- Virtualenv version (if using virtualenv): n/a
+
+Command(s) used to install setuptools (and output):
+
+```
+```
+
+Output of `pip --version` when installing setuptools:
+
+```
+```
+
+## Other notes
diff --git a/.github/workflows/python-tests.yml b/.github/workflows/python-tests.yml
index 71957aba..e3663cf0 100644
--- a/.github/workflows/python-tests.yml
+++ b/.github/workflows/python-tests.yml
@@ -1,4 +1,6 @@
-name: Test suite
+name: >-
+  👷
+  Test suite
 
 on:
   push:
@@ -8,32 +10,55 @@ on:
 
 jobs:
   tests:
-    name: 👷
+    name: >-
+      ${{ matrix.python-version }}
+      /
+      ${{ matrix.os }}
     runs-on: ${{ matrix.os }}
     strategy:
       # max-parallel: 5
       matrix:
         python-version:
         - 3.8
+        - pypy3
         - 3.7
         - 3.6
         - 3.5
-        - 2.7
         os:
-        - ubuntu-18.04
+        - ubuntu-latest
         - ubuntu-16.04
         - macOS-latest
         # - windows-2019
         # - windows-2016
-        env:
-        - TOXENV: python
+
+    env:
+      NETWORK_REQUIRED: 1
+      TOX_PARALLEL_NO_SPINNER: 1
+      TOXENV: python
 
     steps:
     - uses: actions/checkout@master
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v1
+      uses: actions/setup-python@v1.1.1
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Log Python version
+      run: >-
+        python --version
+    - name: Log Python location
+      run: >-
+        which python
+    - name: Log Python env
+      run: >-
+        python -m sysconfig
+    - name: Pip cache
+      uses: actions/cache@v1
       with:
-        version: ${{ matrix.python-version }}
+        path: ~/.cache/pip
+        key: ${{ runner.os }}-pip-${{ hashFiles('setup.cfg') }}
+        restore-keys: |
+          ${{ runner.os }}-pip-
+          ${{ runner.os }}-
     - name: Upgrade pip/setuptools/wheel
       run: >-
         python
@@ -47,15 +72,14 @@ jobs:
     - name: Log installed dists
       run: >-
         python -m pip freeze --all
+    - name: Adjust TOXENV for PyPy
+      if: startsWith(matrix.python-version, 'pypy')
+      run: >-
+        echo "::set-env name=TOXENV::${{ matrix.python-version }}"
     - name: Log env vars
       run: >-
         env
-      env: ${{ matrix.env }}
 
-    - name: Update egg_info based on setup.py in checkout
-      run: >-
-        python -m bootstrap
-      env: ${{ matrix.env }}
     - name: Verify that there's no cached Python modules in sources
       if: >-
         ! startsWith(matrix.os, 'windows-')
@@ -63,14 +87,16 @@ jobs:
         ! 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 }}
+      run: >-
+        python -m
+        tox
+        --parallel auto
+        --notest
+        --skip-missing-interpreters false
     - name: Test with tox
-      run: |
-        ${{ startsWith(matrix.os, 'windows-') && 'setx NETWORK_REQUIRED ' || 'export NETWORK_REQUIRED=' }}1
-        python -m tox \
-        --parallel 0 \
-        -- \
+      run: >-
+        python -m
+        tox
+        --parallel auto
+        --
         --cov
-      env: ${{ matrix.env }}
diff --git a/.gitignore b/.gitignore
index 0c272d1c..90ae8050 100644
--- a/.gitignore
+++ b/.gitignore
@@ -19,3 +19,4 @@ setuptools.egg-info
 .cache
 .idea/
 .pytest_cache/
+.mypy_cache/
diff --git a/.readthedocs.yml b/.readthedocs.yml
index 3aef6b6b..cb10a7f9 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -1,4 +1,6 @@
 python:
   version: 3
-  requirements_file: docs/requirements.txt
+  extra_requirements:
+  - docs
   pip_install: false
+  requirements: docs/requirements.txt
diff --git a/.travis.yml b/.travis.yml
index 263386c8..3e97f353 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -21,11 +21,9 @@ jobs:
   - python: 3.8-dev
   - <<: *latest_py3
     env: TOXENV=docs DISABLE_COVERAGE=1
-  - <<: *latest_py3
-    stage: deploy
-    if: tag IS present
-    script: tox -e release
-    after_success: skip
+  allow_failures:
+  # suppress failures due to pypa/setuptools#2000
+  - python: pypy3
 
 cache: pip
 
@@ -40,8 +38,6 @@ 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 4a81e995..fd3c16ba 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,3 +1,108 @@
+v46.3.1
+-------
+
+No significant changes.
+
+
+v46.3.0
+-------
+
+* #2089: Package index functionality no longer attempts to remove an md5 fragment from the index URL. This functionality, added for distribute #163 is no longer relevant.
+* #2041: Preserve file modes during pkg files copying, but clear read only flag for target afterwards.
+* #2105: Filter ``2to3`` deprecation warnings from ``TestDevelop.test_2to3_user_mode``.
+
+
+v46.2.0
+-------
+
+* #2040: Deprecated the ``bdist_wininst`` command. Binary packages should be built as wheels instead.
+* #2062: Change 'Mac OS X' to 'macOS' in code.
+* #2075: Stop recognizing files ending with ``.dist-info`` as distribution metadata.
+* #2086: Deprecate 'use_2to3' functionality. Packagers are encouraged to use single-source solutions or build tool chains to manage conversions outside of setuptools.
+* #1698: Added documentation for ``build_meta`` (a bare minimum, not completed).
+* #2082: Filter ``lib2to3`` ``PendingDeprecationWarning`` and ``DeprecationWarning`` in tests,
+  because ``lib2to3`` is `deprecated in Python 3.9 <https://bugs.python.org/issue40360>`_.
+
+
+v46.1.3
+-------
+
+No significant changes.
+
+
+v46.1.2
+-------
+
+* #1458: Added template for reporting Python 2 incompatibilities.
+
+
+v46.1.1
+-------
+
+No significant changes.
+
+
+v46.1.0
+-------
+
+* #308: Allow version number normalization to be bypassed by wrapping in a 'setuptools.sic()' call.
+* #1424: Prevent keeping files mode for package_data build. It may break a build if user's package data has read only flag.
+* #1431: In ``easy_install.check_site_dir``, ensure the installation directory exists.
+* #1563: In ``pkg_resources`` prefer ``find_spec`` (PEP 451) to ``find_module``.
+
+Incorporate changes from v44.1.0:
+
+* #1704: Set sys.argv[0] in setup script run by build_meta.__legacy__
+* #1959: Fix for Python 4: replace unsafe six.PY3 with six.PY2
+* #1994: Fixed a bug in the "setuptools.finalize_distribution_options" hook that lead to ignoring the order attribute of entry points managed by this hook.
+
+
+v44.1.0
+-------
+
+* #1704: Set sys.argv[0] in setup script run by build_meta.__legacy__
+* #1959: Fix for Python 4: replace unsafe six.PY3 with six.PY2
+* #1994: Fixed a bug in the "setuptools.finalize_distribution_options" hook that lead to ignoring the order attribute of entry points managed by this hook.
+
+
+v46.0.0
+-------
+
+* #65: Once again as in 3.0, removed the Features feature.
+* #1890: Fix vendored dependencies so importing ``setuptools.extern.some_module`` gives the same object as ``setuptools._vendor.some_module``. This makes Metadata picklable again.
+* #1899: Test suite now fails on warnings.
+* #2011: Fix broken link to distutils docs on package_data
+* #1991: Include pkg_resources test data in sdist, so tests can be executed from it.
+
+
+v45.3.0
+-------
+
+* #1557: Deprecated eggsecutable scripts and updated docs.
+* #1904: Update msvc.py to use CPython 3.8.0 mechanism to find msvc 14+
+
+
+v45.2.0
+-------
+
+* #1905: Fixed defect in _imp, introduced in 41.6.0 when the 'tests' directory is not present.
+* #1941: Improve editable installs with PEP 518 build isolation:
+
+  * The ``--user`` option is now always available. A warning is issued if the user site directory is not available.
+  * The error shown when the install directory is not in ``PYTHONPATH`` has been turned into a warning.
+* #1981: Setuptools now declares its ``tests`` and ``docs`` dependencies in metadata (extras).
+* #1985: Add support for installing scripts in environments where bdist_wininst is missing (i.e. Python 3.9).
+* #1968: Add flake8-2020 to check for misuse of sys.version or sys.version_info.
+
+
+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
 -------
 
diff --git a/MANIFEST.in b/MANIFEST.in
index 16d60e5f..128ae280 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -4,6 +4,7 @@ recursive-include setuptools/tests *.html
 recursive-include docs *.py *.txt *.conf *.css *.css_t Makefile indexsidebar.html
 recursive-include setuptools/_vendor *.py *.txt
 recursive-include pkg_resources *.py *.txt
+recursive-include pkg_resources/tests/data *
 include *.py
 include *.rst
 include MANIFEST.in
diff --git a/README.rst b/README.rst
index da0549a9..9cbf7b86 100644
--- a/README.rst
+++ b/README.rst
@@ -1,8 +1,13 @@
 .. image:: https://img.shields.io/pypi/v/setuptools.svg
-   :target: https://pypi.org/project/setuptools
+   :target: `PyPI link`_
 
-.. image:: https://img.shields.io/readthedocs/setuptools/latest.svg
-    :target: https://setuptools.readthedocs.io
+.. image:: https://img.shields.io/pypi/pyversions/setuptools.svg
+   :target: `PyPI link`_
+
+.. _PyPI link: https://pypi.org/project/setuptools
+
+.. image:: https://dev.azure.com/jaraco/setuptools/_apis/build/status/pypa.setuptools?branchName=master
+   :target: https://dev.azure.com/jaraco/setuptools/_build/latest?definitionId=1&branchName=master
 
 .. image:: https://img.shields.io/travis/pypa/setuptools/master.svg?label=Linux%20CI&logo=travis&logoColor=white
    :target: https://travis-ci.org/pypa/setuptools
@@ -10,14 +15,15 @@
 .. image:: https://img.shields.io/appveyor/ci/pypa/setuptools/master.svg?label=Windows%20CI&logo=appveyor&logoColor=white
    :target: https://ci.appveyor.com/project/pypa/setuptools/branch/master
 
+.. image:: https://img.shields.io/readthedocs/setuptools/latest.svg
+    :target: https://setuptools.readthedocs.io
+
 .. image:: https://img.shields.io/codecov/c/github/pypa/setuptools/master.svg?logo=codecov&logoColor=white
    :target: https://codecov.io/gh/pypa/setuptools
 
 .. image:: https://tidelift.com/badges/github/pypa/setuptools?style=flat
    :target: https://tidelift.com/subscription/pkg/pypi-setuptools?utm_source=pypi-setuptools&utm_medium=readme
 
-.. image:: https://img.shields.io/pypi/pyversions/setuptools.svg
-
 See the `Installation Instructions
 <https://packaging.python.org/installing/>`_ in the Python Packaging
 User's Guide for instructions on installing, upgrading, and uninstalling
diff --git a/appveyor.yml b/appveyor.yml
index fc65a9a7..de4e6c66 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -7,6 +7,15 @@ environment:
   CODECOV_ENV: APPVEYOR_JOB_NAME
 
   matrix:
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+      APPVEYOR_JOB_NAME: "python35-x64-vs2015"
+      PYTHON: "C:\\Python35-x64"
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      APPVEYOR_JOB_NAME: "python35-x64-vs2017"
+      PYTHON: "C:\\Python35-x64"
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
+      APPVEYOR_JOB_NAME: "python35-x64-vs2019"
+      PYTHON: "C:\\Python35-x64"
     - APPVEYOR_JOB_NAME: "python36-x64"
       PYTHON: "C:\\Python36-x64"
     - APPVEYOR_JOB_NAME: "python37-x64"
@@ -28,7 +37,6 @@ 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..ee772682
--- /dev/null
+++ b/azure-pipelines.yml
@@ -0,0 +1,81 @@
+# 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: $(pool_vm_image)
+
+variables:
+- group: Azure secrets
+- name: pool_vm_image
+  value: Ubuntu-18.04
+
+stages:
+- stage: Test
+  jobs:
+
+  - job: 'Test'
+    strategy:
+      matrix:
+        Bionic Python 3.6:
+          python.version: '3.6'
+        Bionic Python 3.8:
+          python.version: '3.8'
+        Windows:
+          python.version: '3.8'
+          pool_vm_image: vs2017-win2016
+        MacOS:
+          python.version: '3.8'
+          pool_vm_image: macos-10.15
+
+      maxParallel: 4
+
+    steps:
+    - task: UsePythonVersion@0
+      inputs:
+        versionSpec: '$(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)
+        TIDELIFT_TOKEN: $(Tidelift-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/1458.change.rst b/changelog.d/1458.change.rst
deleted file mode 100644
index c953127a..00000000
--- a/changelog.d/1458.change.rst
+++ /dev/null
@@ -1 +0,0 @@
-Add minimum sunset date and preamble to Python 2 warning.
diff --git a/docs/build_meta.txt b/docs/build_meta.txt
new file mode 100644
index 00000000..ef9fb2ac
--- /dev/null
+++ b/docs/build_meta.txt
@@ -0,0 +1,89 @@
+=======================================
+Build System Support
+=======================================
+
+What is it?
+-------------
+
+Python packaging has come `a long way <https://www.bernat.tech/pep-517-518/>`_.
+
+The traditional ``setuptools`` way of packgaging Python modules
+uses a ``setup()`` function within the ``setup.py`` script. Commands such as
+``python setup.py bdist`` or ``python setup.py bdist_wheel`` generate a 
+distribution bundle and ``python setup.py install`` installs the distribution. 
+This interface makes it difficult to choose other packaging tools without an 
+overhaul. Because ``setup.py`` scripts allowed for arbitrary execution, it
+proved difficult to provide a reliable user experience across environments
+and history.
+
+`PEP 517 <https://www.python.org/dev/peps/pep-0517/>`_ therefore came to
+rescue and specified a new standard to 
+package and distribute Python modules. Under PEP 517:
+
+    a ``pyproject.toml`` file is used to specify what program to use
+    for generating distribution. 
+
+    Then, two functions provided by the program, ``build_wheel(directory: str)`` 
+    and ``build_sdist(directory: str)`` create the distribution bundle at the 
+    specified ``directory``. The program is free to use its own configuration 
+    script or extend the ``.toml`` file. 
+
+    Lastly, ``pip install *.whl`` or ``pip install *.tar.gz`` does the actual
+    installation. If ``*.whl`` is available, ``pip`` will go ahead and copy
+    the files into ``site-packages`` directory. If not, ``pip`` will look at
+    ``pyproject.toml`` and decide what program to use to 'build from source' 
+    (the default is ``setuptools``)
+
+With this standard, switching between packaging tools becomes a lot easier. ``build_meta``
+implements ``setuptools``' build system support.
+
+How to use it?
+--------------
+
+Starting with a package that you want to distribute. You will need your source
+scripts, a ``pyproject.toml`` file and a ``setup.cfg`` file::
+
+    ~/meowpkg/
+        pyproject.toml
+        setup.cfg
+        meowpkg/__init__.py
+
+The pyproject.toml file is required to specify the build system (i.e. what is 
+being used to package your scripts and install from source). To use it with 
+setuptools, the content would be::
+
+    [build-system]
+    requires = ["setuptools", "wheel"]
+    build-backend = "setuptools.build_meta" 
+
+Use ``setuptools``' `declarative config`_ to specify the package information::
+
+    [metadata]
+    name = meowpkg
+    version = 0.0.1
+    description = a package that meows
+    
+    [options]
+    packages = find:
+
+Now generate the distribution. Although the PyPA is still working to
+`provide a recommended tool <https://github.com/pypa/packaging-problems/issues/219>`_
+to build packages, the `pep517 package <https://pypi.org/project/pep517`_
+provides this functionality. To build the package::
+
+    $ pip install -q pep517
+    $ mkdir dist
+    $ python -m pep517.build .
+
+And now it's done! The ``.whl`` file  and ``.tar.gz`` can then be distributed 
+and installed::
+
+    dist/
+        meowpkg-0.0.1.whl
+        meowpkg-0.0.1.tar.gz
+
+    $ pip install dist/meowpkg-0.0.1.whl
+
+or::
+
+    $ pip install dist/meowpkg-0.0.1.tar.gz
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/history.txt b/docs/history.txt
index 385cfa7e..faf7adfe 100644
--- a/docs/history.txt
+++ b/docs/history.txt
@@ -12,7 +12,7 @@ Credits
 
 * The original design for the ``.egg`` format and the ``pkg_resources`` API was
   co-created by Phillip Eby and Bob Ippolito. Bob also implemented the first
-  version of ``pkg_resources``, and supplied the OS X operating system version
+  version of ``pkg_resources``, and supplied the macOS operating system version
   compatibility algorithm.
 
 * Ian Bicking implemented many early "creature comfort" features of
diff --git a/docs/pkg_resources.txt b/docs/pkg_resources.txt
index b887a923..71568c1a 100644
--- a/docs/pkg_resources.txt
+++ b/docs/pkg_resources.txt
@@ -1621,7 +1621,7 @@ Platform Utilities
 
 ``get_build_platform()``
     Return this platform's identifier string.  For Windows, the return value
-    is ``"win32"``, and for Mac OS X it is a string of the form
+    is ``"win32"``, and for macOS it is a string of the form
     ``"macosx-10.4-ppc"``.  All other platforms return the same uname-based
     string that the ``distutils.util.get_platform()`` function returns.
     This string is the minimum platform version required by distributions built
@@ -1641,7 +1641,7 @@ Platform Utilities
     considered a wildcard, and the platforms are therefore compatible.
     Likewise, if the platform strings are equal, they're also considered
     compatible, and ``True`` is returned.  Currently, the only non-equal
-    platform strings that are considered compatible are Mac OS X platform
+    platform strings that are considered compatible are macOS platform
     strings with the same hardware type (e.g. ``ppc``) and major version
     (e.g. ``10``) with the `provided` platform's minor version being less than
     or equal to the `required` platform's minor version.
@@ -1674,7 +1674,7 @@ File/Path Utilities
     the same filesystem location if they have equal ``normalized_path()``
     values.  Specifically, this is a shortcut for calling ``os.path.realpath``
     and ``os.path.normcase`` on `path`.  Unfortunately, on certain platforms
-    (notably Cygwin and Mac OS X) the ``normcase`` function does not accurately
+    (notably Cygwin and macOS) the ``normcase`` function does not accurately
     reflect the platform's case-sensitivity, so there is always the possibility
     of two apparently-different paths being equal on such platforms.
 
diff --git a/docs/releases.txt b/docs/releases.txt
index 98ba39e8..35b415c2 100644
--- a/docs/releases.txt
+++ b/docs/releases.txt
@@ -3,39 +3,13 @@ Release Process
 ===============
 
 In order to allow for rapid, predictable releases, Setuptools uses a
-mechanical technique for releases, enacted by Travis following a
-successful build of a tagged release per
-`PyPI deployment <https://docs.travis-ci.com/user/deployment/pypi>`_.
-
-Prior to cutting a release, please use `towncrier`_ to update
-``CHANGES.rst`` to summarize the changes since the last release.
-To update the changelog:
-
-1. Install towncrier via ``pip install towncrier`` if not already installed.
-2. Preview the new ``CHANGES.rst`` entry by running
-   ``towncrier --draft --version {new.version.number}`` (enter the desired
-   version number for the next release).  If any changes are needed, make
-   them and generate a new preview until the output is acceptable.  Run
-   ``git add`` for any modified files.
-3. Run ``towncrier --version {new.version.number}`` to stage the changelog
-   updates in git.
-4. Verify that there are no remaining ``changelog.d/*.rst`` files.  If a
-   file was named incorrectly, it may be ignored by towncrier.
-5. Review the updated ``CHANGES.rst`` file.  If any changes are needed,
-   make the edits and stage them via ``git add CHANGES.rst``.
-
-Once the changelog edits are staged and ready to commit, cut a release by
-installing and running ``bump2version --allow-dirty {part}`` where ``part``
-is major, minor, or patch based on the scope of the changes in the
-release. Then, push the commits to the master branch::
-
-    $ git push origin master
-    $ git push --tags
-
-If tests pass, the release will be uploaded to PyPI (from the Python 3.6
-tests).
-
-.. _towncrier: https://pypi.org/project/towncrier/
+mechanical technique for releases, enacted on tagged commits by
+continuous integration.
+
+To finalize a release, run ``tox -e finalize``, review, then push
+the changes.
+
+If tests pass, the release will be uploaded to PyPI.
 
 Release Frequency
 -----------------
diff --git a/docs/requirements.txt b/docs/requirements.txt
index e82df49c..104d68fa 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,6 +1,7 @@
-sphinx!=1.8.0
-pygments-github-lexers==0.0.5
-rst.linker>=1.9
+# keep these in sync with setup.cfg
+sphinx
 jaraco.packaging>=6.1
+rst.linker>=1.9
+pygments-github-lexers==0.0.5
 
 setuptools>=34
diff --git a/docs/setuptools.txt b/docs/setuptools.txt
index e5663fc4..ec58b754 100644
--- a/docs/setuptools.txt
+++ b/docs/setuptools.txt
@@ -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
@@ -371,7 +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.
 
@@ -413,7 +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
@@ -480,7 +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
@@ -500,8 +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/
 
@@ -526,12 +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",
             ]
         }
     )
@@ -560,6 +560,8 @@ Services and Plugins`_.
 "Eggsecutable" Scripts
 ----------------------
 
+.. deprecated:: 45.3.0
+
 Occasionally, there are situations where it's desirable to make an ``.egg``
 file directly executable.  You can do this by including an entry point such
 as the following::
@@ -567,8 +569,8 @@ 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",
             ]
         }
     )
@@ -741,8 +743,8 @@ 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"],
         }
     )
 
@@ -763,9 +765,9 @@ 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 ...
             ],
         }
@@ -801,8 +803,8 @@ setup to this::
         name="Project-A",
         ...
         extras_require={
-            'PDF':  [],
-            'reST': ["docutils>=0.3"],
+            "PDF":  [],
+            "reST": ["docutils>=0.3"],
         }
     )
 
@@ -829,8 +831,8 @@ 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'"
         ]
     )
 
@@ -878,9 +880,9 @@ 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"],
         }
     )
 
@@ -903,15 +905,15 @@ 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"],
         }
     )
 
@@ -926,7 +928,7 @@ 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
@@ -939,7 +941,7 @@ python.org website.  If using the setuptools-specific ``include_package_data``
 argument, files specified by ``package_data`` will *not* be automatically
 added to the manifest unless they are listed in the MANIFEST.in file.)
 
-__ http://docs.python.org/dist/node11.html
+__ https://docs.python.org/3/distutils/setupscript.html#installing-package-data
 
 Sometimes, the ``include_package_data`` or ``package_data`` options alone
 aren't sufficient to precisely define what files you want included.  For
@@ -951,18 +953,18 @@ 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``.
@@ -1096,12 +1098,12 @@ 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(
@@ -1220,7 +1222,7 @@ Before you begin, make sure you have the latest versions of setuptools and 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.
 
@@ -1309,7 +1311,7 @@ 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``
@@ -1327,7 +1329,7 @@ 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.
@@ -1410,7 +1412,7 @@ 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.
@@ -1469,7 +1471,7 @@ 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
@@ -1479,11 +1481,11 @@ 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.
@@ -1500,7 +1502,7 @@ 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
@@ -1800,7 +1802,7 @@ 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
@@ -1848,7 +1850,7 @@ 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
@@ -1873,12 +1875,12 @@ 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.)
@@ -2104,8 +2106,9 @@ Configuring setup() using setup.cfg files
 .. note:: New in 30.3.0 (8 Dec 2016).
 
 .. important::
-    A ``setup.py`` file containing a ``setup()`` function call is still
-    required even if your configuration resides in ``setup.cfg``.
+    If compatibility with legacy builds (i.e. those not using the :pep:`517`
+    build API) is desired, a ``setup.py`` file containing a ``setup()`` function
+    call is still required even if your configuration resides in ``setup.cfg``.
 
 ``Setuptools`` allows using configuration files (usually :file:`setup.cfg`)
 to define a package’s metadata and other options that are normally supplied
@@ -2394,7 +2397,7 @@ 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
@@ -2574,7 +2577,7 @@ 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/netlify.toml b/netlify.toml
index ec21e7be..5828132e 100644
--- a/netlify.toml
+++ b/netlify.toml
@@ -1,5 +1,7 @@
 # Configuration for pull request documentation previews via Netlify
 
+# Netlify relies on there being a ./runtime.txt to indicate Python 3.
+
 [build]
-    publish = "docs/build/html"
+    publish = "build/html"
     command = "pip install tox && tox -e docs"
diff --git a/pkg_resources/__init__.py b/pkg_resources/__init__.py
index 3fa883ce..edd3d2e8 100644
--- a/pkg_resources/__init__.py
+++ b/pkg_resources/__init__.py
@@ -55,7 +55,7 @@ except NameError:
     FileExistsError = OSError
 
 from pkg_resources.extern import six
-from pkg_resources.extern.six.moves import urllib, map, filter
+from pkg_resources.extern.six.moves import map, filter
 
 # capture these to bypass sandboxing
 from os import utime
@@ -179,10 +179,10 @@ def get_supported_platform():
     """Return this platform's maximum compatible version.
 
     distutils.util.get_platform() normally reports the minimum version
-    of Mac OS X that would be required to *use* extensions produced by
+    of macOS that would be required to *use* extensions produced by
     distutils.  But what we want when checking compatibility is to know the
-    version of Mac OS X that we are *running*.  To allow usage of packages that
-    explicitly require a newer version of Mac OS X, we must also know the
+    version of macOS that we are *running*.  To allow usage of packages that
+    explicitly require a newer version of macOS, we must also know the
     current version of the OS.
 
     If this condition occurs for any other platform with a version in its
@@ -192,9 +192,9 @@ def get_supported_platform():
     m = macosVersionString.match(plat)
     if m is not None and sys.platform == "darwin":
         try:
-            plat = 'macosx-%s-%s' % ('.'.join(_macosx_vers()[:2]), m.group(3))
+            plat = 'macosx-%s-%s' % ('.'.join(_macos_vers()[:2]), m.group(3))
         except ValueError:
-            # not Mac OS X
+            # not macOS
             pass
     return plat
 
@@ -365,7 +365,7 @@ def get_provider(moduleOrReq):
     return _find_adapter(_provider_factories, loader)(module)
 
 
-def _macosx_vers(_cache=[]):
+def _macos_vers(_cache=[]):
     if not _cache:
         version = platform.mac_ver()[0]
         # fallback for MacPorts
@@ -381,7 +381,7 @@ def _macosx_vers(_cache=[]):
     return _cache[0]
 
 
-def _macosx_arch(machine):
+def _macos_arch(machine):
     return {'PowerPC': 'ppc', 'Power_Macintosh': 'ppc'}.get(machine, machine)
 
 
@@ -389,18 +389,18 @@ def get_build_platform():
     """Return this platform's string for platform-specific distributions
 
     XXX Currently this is the same as ``distutils.util.get_platform()``, but it
-    needs some hacks for Linux and Mac OS X.
+    needs some hacks for Linux and macOS.
     """
     from sysconfig import get_platform
 
     plat = get_platform()
     if sys.platform == "darwin" and not plat.startswith('macosx-'):
         try:
-            version = _macosx_vers()
+            version = _macos_vers()
             machine = os.uname()[4].replace(" ", "_")
             return "macosx-%d.%d-%s" % (
                 int(version[0]), int(version[1]),
-                _macosx_arch(machine),
+                _macos_arch(machine),
             )
         except ValueError:
             # if someone is running a non-Mac darwin system, this will fall
@@ -426,7 +426,7 @@ def compatible_platforms(provided, required):
         # easy case
         return True
 
-    # Mac OS X special cases
+    # macOS special cases
     reqMac = macosVersionString.match(required)
     if reqMac:
         provMac = macosVersionString.match(provided)
@@ -435,7 +435,7 @@ def compatible_platforms(provided, required):
         if not provMac:
             # this is backwards compatibility for packages built before
             # setuptools 0.6. All packages built after this point will
-            # use the new macosx designation.
+            # use the new macOS designation.
             provDarwin = darwinVersionString.match(provided)
             if provDarwin:
                 dversion = int(provDarwin.group(1))
@@ -443,7 +443,7 @@ def compatible_platforms(provided, required):
                 if dversion == 7 and macosversion >= "10.3" or \
                         dversion == 8 and macosversion >= "10.4":
                     return True
-            # egg isn't macosx or legacy darwin
+            # egg isn't macOS or legacy darwin
             return False
 
         # are they the same major version and machine type?
@@ -1235,12 +1235,13 @@ class ResourceManager:
         mode = os.stat(path).st_mode
         if mode & stat.S_IWOTH or mode & stat.S_IWGRP:
             msg = (
-                "%s is writable by group/others and vulnerable to attack "
-                "when "
-                "used with get_resource_filename. Consider a more secure "
+                "Extraction path is writable by group/others "
+                "and vulnerable to attack when "
+                "used with get_resource_filename ({path}). "
+                "Consider a more secure "
                 "location (set with .set_extraction_path or the "
-                "PYTHON_EGG_CACHE environment variable)." % path
-            )
+                "PYTHON_EGG_CACHE environment variable)."
+            ).format(**locals())
             warnings.warn(msg, UserWarning)
 
     def postprocess(self, tempname, filename):
@@ -2068,11 +2069,14 @@ def find_on_path(importer, path_item, only=False):
 
 
 def dist_factory(path_item, entry, only):
-    """
-    Return a dist_factory for a path_item and entry
-    """
+    """Return a dist_factory for the given entry."""
     lower = entry.lower()
-    is_meta = any(map(lower.endswith, ('.egg-info', '.dist-info')))
+    is_egg_info = lower.endswith('.egg-info')
+    is_dist_info = (
+        lower.endswith('.dist-info') and
+        os.path.isdir(os.path.join(path_item, entry))
+    )
+    is_meta = is_egg_info or is_dist_info
     return (
         distributions_from_metadata
         if is_meta else
@@ -2196,10 +2200,14 @@ def _handle_ns(packageName, path_item):
     if importer is None:
         return None
 
-    # capture warnings due to #1111
-    with warnings.catch_warnings():
-        warnings.simplefilter("ignore")
-        loader = importer.find_module(packageName)
+    # use find_spec (PEP 451) and fall-back to find_module (PEP 302)
+    try:
+        loader = importer.find_spec(packageName).loader
+    except AttributeError:
+        # capture warnings due to #1111
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore")
+            loader = importer.find_module(packageName)
 
     if loader is None:
         return None
@@ -2329,7 +2337,8 @@ 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
@@ -2537,15 +2546,6 @@ class EntryPoint:
         return maps
 
 
-def _remove_md5_fragment(location):
-    if not location:
-        return ''
-    parsed = urllib.parse.urlparse(location)
-    if parsed[-1].startswith('md5='):
-        return urllib.parse.urlunparse(parsed[:-1] + ('',))
-    return location
-
-
 def _version_from_file(lines):
     """
     Given an iterable of lines from a Metadata file, return
@@ -2602,7 +2602,7 @@ class Distribution:
             self.parsed_version,
             self.precedence,
             self.key,
-            _remove_md5_fragment(self.location),
+            self.location,
             self.py_version or '',
             self.platform or '',
         )
@@ -3288,6 +3288,7 @@ 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/api_tests.txt b/pkg_resources/api_tests.txt
index 7ae5a038..ded18800 100644
--- a/pkg_resources/api_tests.txt
+++ b/pkg_resources/api_tests.txt
@@ -290,8 +290,8 @@ Platform Compatibility Rules
 ----------------------------
 
 On the Mac, there are potential compatibility issues for modules compiled
-on newer versions of Mac OS X than what the user is running. Additionally,
-Mac OS X will soon have two platforms to contend with: Intel and PowerPC.
+on newer versions of macOS than what the user is running. Additionally,
+macOS will soon have two platforms to contend with: Intel and PowerPC.
 
 Basic equality works as on other platforms::
 
diff --git a/pkg_resources/extern/__init__.py b/pkg_resources/extern/__init__.py
index c1eb9e99..bf98d8f2 100644
--- a/pkg_resources/extern/__init__.py
+++ b/pkg_resources/extern/__init__.py
@@ -43,13 +43,6 @@ class VendorImporter:
                 __import__(extant)
                 mod = sys.modules[extant]
                 sys.modules[fullname] = mod
-                # mysterious hack:
-                # Remove the reference to the extant package/module
-                # on later Python versions to cause relative imports
-                # in the vendor package to resolve the same modules
-                # as those going through this importer.
-                if prefix and sys.version_info > (3, 3):
-                    del sys.modules[extant]
                 return mod
             except ImportError:
                 pass
diff --git a/pkg_resources/py2_warn.py b/pkg_resources/py2_warn.py
index 1b151956..bfc35234 100644
--- a/pkg_resources/py2_warn.py
+++ b/pkg_resources/py2_warn.py
@@ -12,9 +12,8 @@ msg = textwrap.dedent("""
     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.
+    this message, please follow up at
+    https://bit.ly/setuptools-py2-warning.
     """)
 
 pre = "Setuptools will stop working on Python 2\n"
diff --git a/pkg_resources/tests/test_pkg_resources.py b/pkg_resources/tests/test_pkg_resources.py
index 5960868a..189a8668 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.
     """
@@ -328,6 +330,14 @@ def test_distribution_version_missing_undetected_path():
     assert msg == expected
 
 
+@pytest.mark.parametrize('only', [False, True])
+def test_dist_info_is_not_dir(tmp_path, only):
+    """Test path containing a file with dist-info extension."""
+    dist_info = tmp_path / 'foobar.dist-info'
+    dist_info.touch()
+    assert not pkg_resources.dist_factory(str(tmp_path), str(dist_info), only)
+
+
 class TestDeepVersionLookupDistutils:
     @pytest.fixture
     def env(self, tmpdir):
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/pkg_resources/tests/test_working_set.py b/pkg_resources/tests/test_working_set.py
index b3ca4ea8..7a759bbb 100644
--- a/pkg_resources/tests/test_working_set.py
+++ b/pkg_resources/tests/test_working_set.py
@@ -14,8 +14,8 @@ __metaclass__ = type
 
 def strip_comments(s):
     return '\n'.join(
-        l for l in s.split('\n')
-        if l.strip() and not l.strip().startswith('#')
+        line for line in s.split('\n')
+        if line.strip() and not line.strip().startswith('#')
     )
 
 
diff --git a/pyproject.toml b/pyproject.toml
index f0fd8521..cfdc2574 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,5 +1,9 @@
 [build-system]
-requires = ["setuptools >= 40.8", "wheel"]
+requires = [
+    # avoid self install on Python 2; ref #1996
+    "setuptools >= 40.8; python_version > '3'",
+    "wheel",
+]
 build-backend = "setuptools.build_meta"
 backend-path = ["."]
 
diff --git a/pytest.ini b/pytest.ini
index 0bc1ec01..479a2965 100644
--- a/pytest.ini
+++ b/pytest.ini
@@ -1,10 +1,25 @@
 [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
-	ignore:bdist_wininst command is deprecated
+    # Fail on warnings
+    error
+    # https://github.com/pypa/setuptools/issues/1823
+    ignore:bdist_wininst command is deprecated
+    # Suppress this error; unimportant for CI tests
+    ignore:Extraction path is writable by group/others:UserWarning
+    # Suppress Python 2 deprecation warning
+    ignore:Setuptools will stop working on Python 2:UserWarning
+    # Suppress weird RuntimeWarning.
+    ignore:Parent module 'setuptools' not found while handling absolute import:RuntimeWarning
+    # Suppress use of bytes for filenames on Windows until fixed #2016
+    ignore:The Windows bytes API has been deprecated:DeprecationWarning
+    # Suppress other Python 2 UnicodeWarnings
+    ignore:Unicode equal comparison failed to convert:UnicodeWarning
+    ignore:Unicode unequal comparison failed to convert:UnicodeWarning
+    # https://github.com/pypa/setuptools/issues/2025
+    ignore:direct construction of .*Item has been deprecated:DeprecationWarning
+    # https://github.com/pypa/setuptools/issues/2081
+    ignore:lib2to3 package is deprecated:PendingDeprecationWarning
+    ignore:lib2to3 package is deprecated:DeprecationWarning
diff --git a/runtime.txt b/runtime.txt
new file mode 100644
index 00000000..475ba515
--- /dev/null
+++ b/runtime.txt
@@ -0,0 +1 @@
+3.7
diff --git a/setup.cfg b/setup.cfg
index 18c9e1df..3933714b 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 = 45.0.0
+version = 46.3.1
 description = Easily download, build, install, upgrade, and uninstall Python packages
 author = Python Packaging Authority
 author_email = distutils-sig@python.org
@@ -36,6 +33,7 @@ classifiers =
     License :: OSI Approved :: MIT License
     Operating System :: OS Independent
     Programming Language :: Python :: 3
+    Programming Language :: Python :: 3 :: Only
     Programming Language :: Python :: 3.5
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
@@ -57,5 +55,27 @@ exclude = *.tests
 [options.extras_require]
 ssl =
     wincertstore==0.2; sys_platform=='win32'
+
 certs =
     certifi==2016.9.26
+
+tests =
+    mock
+    pytest-flake8
+    flake8-2020; python_version>="3.6"
+    virtualenv>=13.0.0
+    pytest-virtualenv>=1.2.7
+    pytest>=3.7
+    wheel
+    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.
+
+docs =
+    # Keep these in sync with docs/requirements.txt
+    sphinx
+    jaraco.packaging>=6.1
+    rst.linker>=1.9
+    pygments-github-lexers==0.0.5
diff --git a/setup.py b/setup.py
index 277b6640..1fe18bd1 100755
--- a/setup.py
+++ b/setup.py
@@ -91,7 +91,6 @@ setup_params = dict(
         ],
         "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",
diff --git a/setuptools/__init__.py b/setuptools/__init__.py
index a71b2bbd..811f3fd2 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
@@ -17,7 +16,7 @@ from setuptools.extern.six.moves import filter, map
 
 import setuptools.version
 from setuptools.extension import Extension
-from setuptools.dist import Distribution, Feature
+from setuptools.dist import Distribution
 from setuptools.depends import Require
 from . import monkey
 
@@ -25,13 +24,13 @@ __metaclass__ = type
 
 
 __all__ = [
-    'setup', 'Distribution', 'Feature', 'Command', 'Extension', 'Require',
+    'setup', 'Distribution', 'Command', 'Extension', 'Require',
     'SetuptoolsDeprecationWarning',
     'find_packages'
 ]
 
 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)
@@ -224,5 +224,9 @@ def findall(dir=os.curdir):
     return list(files)
 
 
+class sic(str):
+    """Treat this string as-is (https://en.wikipedia.org/wiki/Sic)"""
+
+
 # Apply monkey patches
 monkey.patch_all()
diff --git a/setuptools/_imp.py b/setuptools/_imp.py
index a3cce9b2..451e45a8 100644
--- a/setuptools/_imp.py
+++ b/setuptools/_imp.py
@@ -17,9 +17,18 @@ C_BUILTIN = 6
 PY_FROZEN = 7
 
 
+def find_spec(module, paths):
+    finder = (
+        importlib.machinery.PathFinder().find_spec
+        if isinstance(paths, list) else
+        importlib.util.find_spec
+    )
+    return finder(module, paths)
+
+
 def find_module(module, paths=None):
     """Just like 'imp.find_module()', but with package support"""
-    spec = importlib.util.find_spec(module, paths)
+    spec = find_spec(module, paths)
     if spec is None:
         raise ImportError("Can't find %s" % module)
     if not spec.has_location and hasattr(spec, 'submodule_search_locations'):
@@ -60,14 +69,14 @@ def find_module(module, paths=None):
 
 
 def get_frozen_object(module, paths=None):
-    spec = importlib.util.find_spec(module, paths)
+    spec = find_spec(module, paths)
     if not spec:
         raise ImportError("Can't find %s" % module)
     return spec.loader.get_code(module)
 
 
 def get_module(module, paths, info):
-    spec = importlib.util.find_spec(module, paths)
+    spec = find_spec(module, paths)
     if not spec:
         raise ImportError("Can't find %s" % module)
     return module_from_spec(spec)
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/bdist_egg.py b/setuptools/command/bdist_egg.py
index 98470f17..1b28d4c9 100644
--- a/setuptools/command/bdist_egg.py
+++ b/setuptools/command/bdist_egg.py
@@ -11,13 +11,14 @@ import os
 import re
 import textwrap
 import marshal
+import warnings
 
 from setuptools.extern import six
 
 from pkg_resources import get_build_platform, Distribution, ensure_directory
 from pkg_resources import EntryPoint
 from setuptools.extension import Library
-from setuptools import Command
+from setuptools import Command, SetuptoolsDeprecationWarning
 
 try:
     # Python 2.7 or >=3.2
@@ -278,6 +279,12 @@ class bdist_egg(Command):
         if ep is None:
             return 'w'  # not an eggsecutable, do it the usual way.
 
+        warnings.warn(
+            "Eggsecutables are deprecated and will be removed in a future "
+            "version.",
+            SetuptoolsDeprecationWarning
+        )
+
         if not ep.attrs or ep.extras:
             raise DistutilsSetupError(
                 "eggsecutable entry point (%r) cannot have 'extras' "
diff --git a/setuptools/command/bdist_wininst.py b/setuptools/command/bdist_wininst.py
index 073de97b..ff4b6345 100644
--- a/setuptools/command/bdist_wininst.py
+++ b/setuptools/command/bdist_wininst.py
@@ -1,4 +1,7 @@
 import distutils.command.bdist_wininst as orig
+import warnings
+
+from setuptools import SetuptoolsDeprecationWarning
 
 
 class bdist_wininst(orig.bdist_wininst):
@@ -14,6 +17,12 @@ class bdist_wininst(orig.bdist_wininst):
         return cmd
 
     def run(self):
+        warnings.warn(
+            "bdist_wininst is deprecated and will be removed in a future "
+            "version. Use bdist_wheel (wheel packages) instead.",
+            SetuptoolsDeprecationWarning
+        )
+
         self._is_running = True
         try:
             orig.bdist_wininst.run(self)
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 1b51e040..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():
diff --git a/setuptools/command/build_py.py b/setuptools/command/build_py.py
index b0314fd4..9d0288a5 100644
--- a/setuptools/command/build_py.py
+++ b/setuptools/command/build_py.py
@@ -7,6 +7,7 @@ import textwrap
 import io
 import distutils.errors
 import itertools
+import stat
 
 from setuptools.extern import six
 from setuptools.extern.six.moves import map, filter, filterfalse
@@ -20,6 +21,10 @@ except ImportError:
             "do nothing"
 
 
+def make_writable(target):
+    os.chmod(target, os.stat(target).st_mode | stat.S_IWRITE)
+
+
 class build_py(orig.build_py, Mixin2to3):
     """Enhanced 'build_py' command that includes data files with packages
 
@@ -121,6 +126,7 @@ class build_py(orig.build_py, Mixin2to3):
                 self.mkpath(os.path.dirname(target))
                 srcfile = os.path.join(src_dir, filename)
                 outf, copied = self.copy_file(srcfile, target)
+                make_writable(target)
                 srcfile = os.path.abspath(srcfile)
                 if (copied and
                         srcfile in self.distribution.convert_2to3_doctests):
diff --git a/setuptools/command/easy_install.py b/setuptools/command/easy_install.py
index 426301d6..5a9576ff 100644
--- a/setuptools/command/easy_install.py
+++ b/setuptools/command/easy_install.py
@@ -1,4 +1,3 @@
-#!/usr/bin/env python
 """
 Easy Install
 ------------
@@ -121,7 +120,8 @@ 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):
@@ -156,19 +156,16 @@ class easy_install(Command):
          "allow building eggs from local checkouts"),
         ('version', None, "print version information and exit"),
         ('no-find-links', None,
-         "Don't load find-links defined in packages being installed")
+         "Don't load find-links defined in packages being installed"),
+        ('user', None, "install in user site-package '%s'" % site.USER_SITE)
     ]
     boolean_options = [
         'zip-ok', 'multi-version', 'exclude-scripts', 'upgrade', 'always-copy',
         'editable',
-        'no-deps', 'local-snapshots-ok', 'version'
+        'no-deps', 'local-snapshots-ok', 'version',
+        'user'
     ]
 
-    if site.ENABLE_USER_SITE:
-        help_msg = "install in user site-package '%s'" % site.USER_SITE
-        user_options.append(('user', None, help_msg))
-        boolean_options.append('user')
-
     negative_opt = {'always-unzip': 'zip-ok'}
     create_index = PackageIndex
 
@@ -272,6 +269,9 @@ class easy_install(Command):
             self.config_vars['userbase'] = self.install_userbase
             self.config_vars['usersite'] = self.install_usersite
 
+        elif self.user:
+            log.warn("WARNING: The user site-packages directory is disabled.")
+
         self._fix_install_dir_for_user_site()
 
         self.expand_basedirs()
@@ -414,8 +414,8 @@ class easy_install(Command):
         if show_deprecation:
             self.announce(
                 "WARNING: The easy_install command is deprecated "
-                "and will be removed in a future version."
-                , log.WARN,
+                "and will be removed in a future version.",
+                log.WARN,
             )
         if self.verbose != self.distribution.verbose:
             log.set_verbosity(self.verbose)
@@ -459,6 +459,12 @@ class easy_install(Command):
         instdir = normalize_path(self.install_dir)
         pth_file = os.path.join(instdir, 'easy-install.pth')
 
+        if not os.path.exists(instdir):
+            try:
+                os.makedirs(instdir)
+            except (OSError, IOError):
+                self.cant_write_to_target()
+
         # Is it a configured, PYTHONPATH, implicit, or explicit site dir?
         is_site_dir = instdir in self.all_site_dirs
 
@@ -478,8 +484,9 @@ class easy_install(Command):
                 self.cant_write_to_target()
 
         if not is_site_dir and not self.multi_version:
-            # Can't install non-multi to non-site dir
-            raise DistutilsError(self.no_default_version_msg())
+            # Can't install non-multi to non-site dir with easy_install
+            pythonpath = os.environ.get('PYTHONPATH', '')
+            log.warn(self.__no_default_msg, self.install_dir, pythonpath)
 
         if is_site_dir:
             if self.pth_file is None:
@@ -507,13 +514,13 @@ 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
@@ -529,7 +536,7 @@ 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,)
@@ -1093,13 +1100,13 @@ 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"""
@@ -1124,7 +1131,7 @@ 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)
@@ -1307,11 +1314,8 @@ 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()
-
-    def no_default_version_msg(self):
-        template = self.__no_default_msg
-        return template % (self.install_dir, os.environ.get('PYTHONPATH', ''))
+        Please make the appropriate changes for your system and try again.
+        """).strip()
 
     def install_site_py(self):
         """Make sure there's a site.py in the target dir, if needed"""
@@ -2093,7 +2097,8 @@ 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)
@@ -2342,6 +2347,8 @@ 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 a5c5a2fc..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:
@@ -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_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/install_scripts.py b/setuptools/command/install_scripts.py
index 16234273..8c9a15e2 100644
--- a/setuptools/command/install_scripts.py
+++ b/setuptools/command/install_scripts.py
@@ -32,8 +32,11 @@ class install_scripts(orig.install_scripts):
         )
         bs_cmd = self.get_finalized_command('build_scripts')
         exec_param = getattr(bs_cmd, 'executable', None)
-        bw_cmd = self.get_finalized_command("bdist_wininst")
-        is_wininst = getattr(bw_cmd, '_is_running', False)
+        try:
+            bw_cmd = self.get_finalized_command("bdist_wininst")
+            is_wininst = getattr(bw_cmd, '_is_running', False)
+        except ImportError:
+            is_wininst = False
         writer = ei.ScriptWriter
         if is_wininst:
             exec_param = "python.exe"
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/test.py b/setuptools/command/test.py
index f6470e9c..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 = not six.PY2 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:
diff --git a/setuptools/command/upload_docs.py b/setuptools/command/upload_docs.py
index 130a0cb6..0351da77 100644
--- a/setuptools/command/upload_docs.py
+++ b/setuptools/command/upload_docs.py
@@ -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):
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 fe5adf46..fe64afa9 100644
--- a/setuptools/dist.py
+++ b/setuptools/dist.py
@@ -19,9 +19,7 @@ import itertools
 from collections import defaultdict
 from email import message_from_file
 
-from distutils.errors import (
-    DistutilsOptionError, DistutilsPlatformError, DistutilsSetupError,
-)
+from distutils.errors import DistutilsOptionError, DistutilsSetupError
 from distutils.util import rfc822_escape
 from distutils.version import StrictVersion
 
@@ -32,7 +30,7 @@ from setuptools.extern.six.moves import map, filter, filterfalse
 
 from . import SetuptoolsDeprecationWarning
 
-from setuptools.depends import Require
+import setuptools
 from setuptools import windows_support
 from setuptools.monkey import get_unpatched
 from setuptools.config import parse_configuration
@@ -162,7 +160,7 @@ 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)
@@ -338,7 +336,7 @@ _Distribution = get_unpatched(distutils.core.Distribution)
 
 
 class Distribution(_Distribution):
-    """Distribution with support for features, tests, and package data
+    """Distribution with support for tests and package data
 
     This is an enhanced version of 'distutils.dist.Distribution' that
     effectively adds the following new optional keyword arguments to 'setup()':
@@ -365,21 +363,6 @@ class Distribution(_Distribution):
         EasyInstall and requests one of your extras, the corresponding
         additional requirements will be installed if needed.
 
-     'features' **deprecated** -- a dictionary mapping option names to
-        'setuptools.Feature'
-        objects.  Features are a portion of the distribution that can be
-        included or excluded based on user options, inter-feature dependencies,
-        and availability on the current system.  Excluded features are omitted
-        from all setup commands, including source and binary distributions, so
-        you can create multiple distributions from the same source tree.
-        Feature names should be valid Python identifiers, except that they may
-        contain the '-' (minus) sign.  Features can be included or excluded
-        via the command line options '--with-X' and '--without-X', where 'X' is
-        the name of the feature.  Whether a feature is included by default, and
-        whether you are allowed to control this from the command line, is
-        determined by the Feature object.  See the 'Feature' class for more
-        information.
-
      'test_suite' -- the name of a test suite to run for the 'test' command.
         If the user runs 'python setup.py test', the package will be installed,
         and the named test suite will be run.  The format is the same as
@@ -401,8 +384,7 @@ class Distribution(_Distribution):
     for manipulating the distribution's contents.  For example, the 'include()'
     and 'exclude()' methods can be thought of as in-place add and subtract
     commands that add or remove packages, modules, extensions, and so on from
-    the distribution.  They are used by the feature subsystem to configure the
-    distribution for the included and excluded features.
+    the distribution.
     """
 
     _DISTUTILS_UNSUPPORTED_METADATA = {
@@ -432,10 +414,6 @@ class Distribution(_Distribution):
         if not have_package_data:
             self.package_data = {}
         attrs = attrs or {}
-        if 'features' in attrs or 'require_features' in attrs:
-            Feature.warn_deprecated()
-        self.require_features = []
-        self.features = {}
         self.dist_files = []
         # Filter-out setuptools' specific options.
         self.src_root = attrs.pop("src_root", None)
@@ -461,30 +439,40 @@ class Distribution(_Distribution):
                 value = default() if default else None
             setattr(self.metadata, option, value)
 
-        if isinstance(self.metadata.version, numbers.Number):
+        self.metadata.version = self._normalize_version(
+            self._validate_version(self.metadata.version))
+        self._finalize_requires()
+
+    @staticmethod
+    def _normalize_version(version):
+        if isinstance(version, setuptools.sic) or version is None:
+            return version
+
+        normalized = str(packaging.version.Version(version))
+        if version != normalized:
+            tmpl = "Normalizing '{version}' to '{normalized}'"
+            warnings.warn(tmpl.format(**locals()))
+            return normalized
+        return version
+
+    @staticmethod
+    def _validate_version(version):
+        if isinstance(version, numbers.Number):
             # Some people apparently take "version number" too literally :)
-            self.metadata.version = str(self.metadata.version)
+            version = str(version)
 
-        if self.metadata.version is not None:
+        if version is not None:
             try:
-                ver = packaging.version.Version(self.metadata.version)
-                normalized_version = str(ver)
-                if self.metadata.version != normalized_version:
-                    warnings.warn(
-                        "Normalizing '%s' to '%s'" % (
-                            self.metadata.version,
-                            normalized_version,
-                        )
-                    )
-                    self.metadata.version = normalized_version
+                packaging.version.Version(version)
             except (packaging.version.InvalidVersion, TypeError):
                 warnings.warn(
                     "The version specified (%r) is an invalid version, this "
                     "may not work as expected with newer versions of "
                     "setuptools, pip, and PyPI. Please see PEP 440 for more "
-                    "details." % self.metadata.version
+                    "details." % version
                 )
-        self._finalize_requires()
+                return setuptools.sic(version)
+        return version
 
     def _finalize_requires(self):
         """
@@ -702,17 +690,6 @@ class Distribution(_Distribution):
                             ignore_option_errors=ignore_option_errors)
         self._finalize_requires()
 
-    def parse_command_line(self):
-        """Process features after parsing command line options"""
-        result = _Distribution.parse_command_line(self)
-        if self.features:
-            self._finalize_features()
-        return result
-
-    def _feature_attrname(self, name):
-        """Convert feature name to corresponding option attribute name"""
-        return 'with_' + name.replace('-', '_')
-
     def fetch_build_eggs(self, requires):
         """Resolve pre-setup requirements"""
         resolved_dists = pkg_resources.working_set.resolve(
@@ -731,13 +708,13 @@ class Distribution(_Distribution):
         to influence the order of execution. Smaller numbers
         go first and the default is 0.
         """
-        hook_key = 'setuptools.finalize_distribution_options'
+        group = 'setuptools.finalize_distribution_options'
 
         def by_order(hook):
             return getattr(hook, 'order', 0)
-        eps = pkg_resources.iter_entry_points(hook_key)
+        eps = map(lambda e: e.load(), pkg_resources.iter_entry_points(group))
         for ep in sorted(eps, key=by_order):
-            ep.load()(self)
+            ep(self)
 
     def _finalize_setup_keywords(self):
         for ep in pkg_resources.iter_entry_points('distutils.setup_keywords'):
@@ -776,53 +753,6 @@ class Distribution(_Distribution):
         from setuptools.installer import fetch_build_egg
         return fetch_build_egg(self, req)
 
-    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()
-
-        for name, feature in self.features.items():
-            self._set_feature(name, None)
-            feature.validate(self)
-
-            if feature.optional:
-                descr = feature.description
-                incdef = ' (default)'
-                excdef = ''
-                if not feature.include_by_default():
-                    excdef, incdef = incdef, excdef
-
-                new = (
-                    ('with-' + name, None, 'include ' + descr + incdef),
-                    ('without-' + name, None, 'exclude ' + descr + excdef),
-                )
-                go.extend(new)
-                no['without-' + name] = 'with-' + name
-
-        self.global_options = self.feature_options = go + self.global_options
-        self.negative_opt = self.feature_negopt = no
-
-    def _finalize_features(self):
-        """Add/remove features and resolve dependencies between them"""
-
-        # First, flag all the enabled items (and thus their dependencies)
-        for name, feature in self.features.items():
-            enabled = self.feature_is_included(name)
-            if enabled or (enabled is None and feature.include_by_default()):
-                feature.include_in(self)
-                self._set_feature(name, 1)
-
-        # Then disable the rest, so that off-by-default features don't
-        # get flagged as errors when they're required by an enabled feature
-        for name, feature in self.features.items():
-            if not self.feature_is_included(name):
-                feature.exclude_from(self)
-                self._set_feature(name, 0)
-
     def get_command_class(self, command):
         """Pluggable version of get_command_class()"""
         if command in self.cmdclass:
@@ -852,25 +782,6 @@ class Distribution(_Distribution):
                 self.cmdclass[ep.name] = cmdclass
         return _Distribution.get_command_list(self)
 
-    def _set_feature(self, name, status):
-        """Set feature's inclusion status"""
-        setattr(self, self._feature_attrname(name), status)
-
-    def feature_is_included(self, name):
-        """Return 1 if feature is included, 0 if excluded, 'None' if unknown"""
-        return getattr(self, self._feature_attrname(name))
-
-    def include_feature(self, name):
-        """Request inclusion of feature named 'name'"""
-
-        if self.feature_is_included(name) == 0:
-            descr = self.features[name].description
-            raise DistutilsOptionError(
-                descr + " is required, but was excluded or is not available"
-            )
-        self.features[name].include_in(self)
-        self._set_feature(name, 1)
-
     def include(self, **attrs):
         """Add items to distribution that are named in keyword arguments
 
@@ -1115,160 +1026,6 @@ class Distribution(_Distribution):
                 sys.stdout.detach(), encoding, errors, newline, line_buffering)
 
 
-class Feature:
-    """
-    **deprecated** -- The `Feature` facility was never completely implemented
-    or supported, `has reported issues
-    <https://github.com/pypa/setuptools/issues/58>`_ and will be removed in
-    a future version.
-
-    A subset of the distribution that can be excluded if unneeded/wanted
-
-    Features are created using these keyword arguments:
-
-      'description' -- a short, human readable description of the feature, to
-         be used in error messages, and option help messages.
-
-      'standard' -- if true, the feature is included by default if it is
-         available on the current system.  Otherwise, the feature is only
-         included if requested via a command line '--with-X' option, or if
-         another included feature requires it.  The default setting is 'False'.
-
-      'available' -- if true, the feature is available for installation on the
-         current system.  The default setting is 'True'.
-
-      'optional' -- if true, the feature's inclusion can be controlled from the
-         command line, using the '--with-X' or '--without-X' options.  If
-         false, the feature's inclusion status is determined automatically,
-         based on 'availabile', 'standard', and whether any other feature
-         requires it.  The default setting is 'True'.
-
-      'require_features' -- a string or sequence of strings naming features
-         that should also be included if this feature is included.  Defaults to
-         empty list.  May also contain 'Require' objects that should be
-         added/removed from the distribution.
-
-      'remove' -- a string or list of strings naming packages to be removed
-         from the distribution if this feature is *not* included.  If the
-         feature *is* included, this argument is ignored.  This argument exists
-         to support removing features that "crosscut" a distribution, such as
-         defining a 'tests' feature that removes all the 'tests' subpackages
-         provided by other features.  The default for this argument is an empty
-         list.  (Note: the named package(s) or modules must exist in the base
-         distribution when the 'setup()' function is initially called.)
-
-      other keywords -- any other keyword arguments are saved, and passed to
-         the distribution's 'include()' and 'exclude()' methods when the
-         feature is included or excluded, respectively.  So, for example, you
-         could pass 'packages=["a","b"]' to cause packages 'a' and 'b' to be
-         added or removed from the distribution as appropriate.
-
-    A feature must include at least one 'requires', 'remove', or other
-    keyword argument.  Otherwise, it can't affect the distribution in any way.
-    Note also that you can subclass 'Feature' to create your own specialized
-    feature types that modify the distribution in other ways when included or
-    excluded.  See the docstrings for the various methods here for more detail.
-    Aside from the methods, the only feature attributes that distributions look
-    at are 'description' and 'optional'.
-    """
-
-    @staticmethod
-    def warn_deprecated():
-        msg = (
-            "Features are deprecated and will be removed in a future "
-            "version. See https://github.com/pypa/setuptools/issues/65."
-        )
-        warnings.warn(msg, DistDeprecationWarning, stacklevel=3)
-
-    def __init__(
-            self, description, standard=False, available=True,
-            optional=True, require_features=(), remove=(), **extras):
-        self.warn_deprecated()
-
-        self.description = description
-        self.standard = standard
-        self.available = available
-        self.optional = optional
-        if isinstance(require_features, (str, Require)):
-            require_features = require_features,
-
-        self.require_features = [
-            r for r in require_features if isinstance(r, str)
-        ]
-        er = [r for r in require_features if not isinstance(r, str)]
-        if er:
-            extras['require_features'] = er
-
-        if isinstance(remove, str):
-            remove = remove,
-        self.remove = remove
-        self.extras = extras
-
-        if not remove and not require_features and not extras:
-            raise DistutilsSetupError(
-                "Feature %s: must define 'require_features', 'remove', or "
-                "at least one of 'packages', 'py_modules', etc."
-            )
-
-    def include_by_default(self):
-        """Should this feature be included by default?"""
-        return self.available and self.standard
-
-    def include_in(self, dist):
-        """Ensure feature and its requirements are included in distribution
-
-        You may override this in a subclass to perform additional operations on
-        the distribution.  Note that this method may be called more than once
-        per feature, and so should be idempotent.
-
-        """
-
-        if not self.available:
-            raise DistutilsPlatformError(
-                self.description + " is required, "
-                "but is not available on this platform"
-            )
-
-        dist.include(**self.extras)
-
-        for f in self.require_features:
-            dist.include_feature(f)
-
-    def exclude_from(self, dist):
-        """Ensure feature is excluded from distribution
-
-        You may override this in a subclass to perform additional operations on
-        the distribution.  This method will be called at most once per
-        feature, and only after all included features have been asked to
-        include themselves.
-        """
-
-        dist.exclude(**self.extras)
-
-        if self.remove:
-            for item in self.remove:
-                dist.exclude_package(item)
-
-    def validate(self, dist):
-        """Verify that feature makes sense in context of distribution
-
-        This method is called by the distribution just before it parses its
-        command line.  It checks to ensure that the 'remove' attribute, if any,
-        contains only valid package/module names that are present in the base
-        distribution when 'setup()' is called.  You may override it in a
-        subclass to perform any other required validation of the feature
-        against a target distribution.
-        """
-
-        for item in self.remove:
-            if not dist.has_contents_for(item):
-                raise DistutilsSetupError(
-                    "%s wants to be able to remove %s, but the distribution"
-                    " doesn't contain any packages or modules under %s"
-                    % (self.description, item, item)
-                )
-
-
 class DistDeprecationWarning(SetuptoolsDeprecationWarning):
     """Class for warning about deprecations in dist in
     setuptools. Not ignored by default, unlike DeprecationWarning."""
diff --git a/setuptools/extern/__init__.py b/setuptools/extern/__init__.py
index e8c616f9..4e79aa17 100644
--- a/setuptools/extern/__init__.py
+++ b/setuptools/extern/__init__.py
@@ -43,13 +43,6 @@ class VendorImporter:
                 __import__(extant)
                 mod = sys.modules[extant]
                 sys.modules[fullname] = mod
-                # mysterious hack:
-                # Remove the reference to the extant package/module
-                # on later Python versions to cause relative imports
-                # in the vendor package to resolve the same modules
-                # as those going through this importer.
-                if sys.version_info >= (3, ):
-                    del sys.modules[extant]
                 return mod
             except ImportError:
                 pass
diff --git a/setuptools/installer.py b/setuptools/installer.py
index 9f8be2ef..1f183bd9 100644
--- a/setuptools/installer.py
+++ b/setuptools/installer.py
@@ -64,8 +64,8 @@ def fetch_build_egg(dist, req):
         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
+            '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.
diff --git a/setuptools/lib2to3_ex.py b/setuptools/lib2to3_ex.py
index 4b1a73fe..017f7285 100644
--- a/setuptools/lib2to3_ex.py
+++ b/setuptools/lib2to3_ex.py
@@ -7,11 +7,13 @@ Customized Mixin2to3 support:
 This module raises an ImportError on Python 2.
 """
 
+import warnings
 from distutils.util import Mixin2to3 as _Mixin2to3
 from distutils import log
 from lib2to3.refactor import RefactoringTool, get_fixers_from_package
 
 import setuptools
+from ._deprecation_warning import SetuptoolsDeprecationWarning
 
 
 class DistutilsRefactoringTool(RefactoringTool):
@@ -33,6 +35,13 @@ class Mixin2to3(_Mixin2to3):
             return
         if not files:
             return
+
+        warnings.warn(
+            "2to3 support is deprecated. If the project still "
+            "requires Python 2 support, please migrate to "
+            "a single-codebase solution or employ an "
+            "independent conversion process.",
+            SetuptoolsDeprecationWarning)
         log.info("Fixing " + " ".join(files))
         self.__build_fixer_names()
         self.__exclude_fixers()
diff --git a/setuptools/msvc.py b/setuptools/msvc.py
index 2ffe1c81..213e39c9 100644
--- a/setuptools/msvc.py
+++ b/setuptools/msvc.py
@@ -26,6 +26,7 @@ from os.path import join, isfile, isdir, dirname
 import sys
 import platform
 import itertools
+import subprocess
 import distutils.errors
 from setuptools.extern.packaging.version import LegacyVersion
 
@@ -142,6 +143,154 @@ def msvc9_query_vcvarsall(ver, arch='x86', *args, **kwargs):
         raise
 
 
+def _msvc14_find_vc2015():
+    """Python 3.8 "distutils/_msvccompiler.py" backport"""
+    try:
+        key = winreg.OpenKey(
+            winreg.HKEY_LOCAL_MACHINE,
+            r"Software\Microsoft\VisualStudio\SxS\VC7",
+            0,
+            winreg.KEY_READ | winreg.KEY_WOW64_32KEY
+        )
+    except OSError:
+        return None, None
+
+    best_version = 0
+    best_dir = None
+    with key:
+        for i in itertools.count():
+            try:
+                v, vc_dir, vt = winreg.EnumValue(key, i)
+            except OSError:
+                break
+            if v and vt == winreg.REG_SZ and isdir(vc_dir):
+                try:
+                    version = int(float(v))
+                except (ValueError, TypeError):
+                    continue
+                if version >= 14 and version > best_version:
+                    best_version, best_dir = version, vc_dir
+    return best_version, best_dir
+
+
+def _msvc14_find_vc2017():
+    """Python 3.8 "distutils/_msvccompiler.py" backport
+
+    Returns "15, path" based on the result of invoking vswhere.exe
+    If no install is found, returns "None, None"
+
+    The version is returned to avoid unnecessarily changing the function
+    result. It may be ignored when the path is not None.
+
+    If vswhere.exe is not available, by definition, VS 2017 is not
+    installed.
+    """
+    root = environ.get("ProgramFiles(x86)") or environ.get("ProgramFiles")
+    if not root:
+        return None, None
+
+    try:
+        path = subprocess.check_output([
+            join(root, "Microsoft Visual Studio", "Installer", "vswhere.exe"),
+            "-latest",
+            "-prerelease",
+            "-requires", "Microsoft.VisualStudio.Component.VC.Tools.x86.x64",
+            "-property", "installationPath",
+            "-products", "*",
+        ]).decode(encoding="mbcs", errors="strict").strip()
+    except (subprocess.CalledProcessError, OSError, UnicodeDecodeError):
+        return None, None
+
+    path = join(path, "VC", "Auxiliary", "Build")
+    if isdir(path):
+        return 15, path
+
+    return None, None
+
+
+PLAT_SPEC_TO_RUNTIME = {
+    'x86': 'x86',
+    'x86_amd64': 'x64',
+    'x86_arm': 'arm',
+    'x86_arm64': 'arm64'
+}
+
+
+def _msvc14_find_vcvarsall(plat_spec):
+    """Python 3.8 "distutils/_msvccompiler.py" backport"""
+    _, best_dir = _msvc14_find_vc2017()
+    vcruntime = None
+
+    if plat_spec in PLAT_SPEC_TO_RUNTIME:
+        vcruntime_plat = PLAT_SPEC_TO_RUNTIME[plat_spec]
+    else:
+        vcruntime_plat = 'x64' if 'amd64' in plat_spec else 'x86'
+
+    if best_dir:
+        vcredist = join(best_dir, "..", "..", "redist", "MSVC", "**",
+                        vcruntime_plat, "Microsoft.VC14*.CRT",
+                        "vcruntime140.dll")
+        try:
+            import glob
+            vcruntime = glob.glob(vcredist, recursive=True)[-1]
+        except (ImportError, OSError, LookupError):
+            vcruntime = None
+
+    if not best_dir:
+        best_version, best_dir = _msvc14_find_vc2015()
+        if best_version:
+            vcruntime = join(best_dir, 'redist', vcruntime_plat,
+                             "Microsoft.VC140.CRT", "vcruntime140.dll")
+
+    if not best_dir:
+        return None, None
+
+    vcvarsall = join(best_dir, "vcvarsall.bat")
+    if not isfile(vcvarsall):
+        return None, None
+
+    if not vcruntime or not isfile(vcruntime):
+        vcruntime = None
+
+    return vcvarsall, vcruntime
+
+
+def _msvc14_get_vc_env(plat_spec):
+    """Python 3.8 "distutils/_msvccompiler.py" backport"""
+    if "DISTUTILS_USE_SDK" in environ:
+        return {
+            key.lower(): value
+            for key, value in environ.items()
+        }
+
+    vcvarsall, vcruntime = _msvc14_find_vcvarsall(plat_spec)
+    if not vcvarsall:
+        raise distutils.errors.DistutilsPlatformError(
+            "Unable to find vcvarsall.bat"
+        )
+
+    try:
+        out = subprocess.check_output(
+            'cmd /u /c "{}" {} && set'.format(vcvarsall, plat_spec),
+            stderr=subprocess.STDOUT,
+        ).decode('utf-16le', errors='replace')
+    except subprocess.CalledProcessError as exc:
+        raise distutils.errors.DistutilsPlatformError(
+            "Error executing {}".format(exc.cmd)
+        )
+
+    env = {
+        key.lower(): value
+        for key, _, value in
+        (line.partition('=') for line in out.splitlines())
+        if key and value
+    }
+
+    if vcruntime:
+        env['py_vcruntime_redist'] = vcruntime
+    return env
+
+
 def msvc14_get_vc_env(plat_spec):
     """
     Patched "distutils._msvccompiler._get_vc_env" for support extra
@@ -159,16 +308,10 @@ def msvc14_get_vc_env(plat_spec):
     dict
         environment
     """
-    # Try to get environment from vcvarsall.bat (Classical way)
-    try:
-        return get_unpatched(msvc14_get_vc_env)(plat_spec)
-    except distutils.errors.DistutilsPlatformError:
-        # Pass error Vcvarsall.bat is missing
-        pass
 
-    # If error, try to set environment directly
+    # Always use backport from CPython 3.8
     try:
-        return EnvironmentInfo(plat_spec, vc_min_ver=14.0).return_env()
+        return _msvc14_get_vc_env(plat_spec)
     except distutils.errors.DistutilsPlatformError as exc:
         _augment_exception(exc, 14.0)
         raise
@@ -544,7 +687,7 @@ 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 +1368,7 @@ 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 +1417,16 @@ 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..0744ea2a 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):
@@ -348,6 +349,8 @@ class PackageIndex(Environment):
         f = self.open_url(url, tmpl % url)
         if f is None:
             return
+        if isinstance(f, urllib.error.HTTPError) and f.code == 401:
+            self.info("Authentication error: %s" % f.msg)
         self.fetched_urls[f.url] = True
         if 'html' not in f.headers.get('content-type', '').lower():
             f.close()  # not html, we can't process it
@@ -1050,7 +1053,7 @@ def open_with_auth(url, opener=urllib.request.urlopen):
     parsed = urllib.parse.urlparse(url)
     scheme, netloc, path, params, query, frag = parsed
 
-    # Double scheme does not raise on Mac OS X as revealed by a
+    # Double scheme does not raise on macOS as revealed by a
     # failing test. We would expect "nonnumeric port". Refs #20.
     if netloc.endswith(':'):
         raise http_client.InvalidURL("nonnumeric port: ''")
@@ -1092,7 +1095,8 @@ 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/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..6377d785 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', 'ack_2to3'
 ]
 
 
@@ -16,3 +16,5 @@ fail_on_ascii = pytest.mark.xfail(is_ascii, reason="Test fails in this locale")
 
 py2_only = pytest.mark.skipif(not PY2, reason="Test runs on Python 2 only")
 py3_only = pytest.mark.skipif(not PY3, reason="Test runs on Python 3 only")
+
+ack_2to3 = pytest.mark.filterwarnings('ignore:2to3 support is deprecated')
diff --git a/tests/requirements.txt b/setuptools/tests/requirements.txt
index 4b5e0eeb..19bf5aef 100644
--- a/tests/requirements.txt
+++ b/setuptools/tests/requirements.txt
@@ -1,5 +1,6 @@
 mock
 pytest-flake8
+flake8-2020; python_version>="3.6"
 virtualenv>=13.0.0
 pytest-virtualenv>=1.2.7
 pytest>=3.7
diff --git a/setuptools/tests/test_bdist_deprecations.py b/setuptools/tests/test_bdist_deprecations.py
new file mode 100644
index 00000000..704164aa
--- /dev/null
+++ b/setuptools/tests/test_bdist_deprecations.py
@@ -0,0 +1,23 @@
+"""develop tests
+"""
+import mock
+
+import pytest
+
+from setuptools.dist import Distribution
+from setuptools import SetuptoolsDeprecationWarning
+
+
+@mock.patch("distutils.command.bdist_wininst.bdist_wininst")
+def test_bdist_wininst_warning(distutils_cmd):
+    dist = Distribution(dict(
+        script_name='setup.py',
+        script_args=['bdist_wininst'],
+        name='foo',
+        py_modules=['hi'],
+    ))
+    dist.parse_command_line()
+    with pytest.warns(SetuptoolsDeprecationWarning):
+        dist.run_commands()
+
+    distutils_cmd.run.assert_called_once()
diff --git a/setuptools/tests/test_bdist_egg.py b/setuptools/tests/test_bdist_egg.py
index fb5b90b1..8760ea30 100644
--- a/setuptools/tests/test_bdist_egg.py
+++ b/setuptools/tests/test_bdist_egg.py
@@ -7,6 +7,7 @@ import zipfile
 import pytest
 
 from setuptools.dist import Distribution
+from setuptools import SetuptoolsDeprecationWarning
 
 from . import contexts
 
@@ -64,3 +65,17 @@ class Test:
         names = list(zi.filename for zi in zip.filelist)
         assert 'hi.pyc' in names
         assert 'hi.py' not in names
+
+    def test_eggsecutable_warning(self, setup_context, user_override):
+        dist = Distribution(dict(
+            script_name='setup.py',
+            script_args=['bdist_egg'],
+            name='foo',
+            py_modules=['hi'],
+            entry_points={
+                'setuptools.installation':
+                    ['eggsecutable = my_package.some_module:main_func']},
+        ))
+        dist.parse_command_line()
+        with pytest.warns(SetuptoolsDeprecationWarning):
+            dist.run_commands()
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 326b4f5d..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"""
 
@@ -406,6 +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__'
@@ -417,3 +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_build_py.py b/setuptools/tests/test_build_py.py
index b3a99f56..78a31ac4 100644
--- a/setuptools/tests/test_build_py.py
+++ b/setuptools/tests/test_build_py.py
@@ -1,4 +1,8 @@
 import os
+import stat
+import shutil
+
+import pytest
 
 from setuptools.dist import Distribution
 
@@ -20,3 +24,61 @@ def test_directories_in_package_data_glob(tmpdir_cwd):
     os.makedirs('path/subpath')
     dist.parse_command_line()
     dist.run_commands()
+
+
+def test_read_only(tmpdir_cwd):
+    """
+    Ensure read-only flag is not preserved in copy
+    for package modules and package data, as that
+    causes problems with deleting read-only files on
+    Windows.
+
+    #1451
+    """
+    dist = Distribution(dict(
+        script_name='setup.py',
+        script_args=['build_py'],
+        packages=['pkg'],
+        package_data={'pkg': ['data.dat']},
+        name='pkg',
+    ))
+    os.makedirs('pkg')
+    open('pkg/__init__.py', 'w').close()
+    open('pkg/data.dat', 'w').close()
+    os.chmod('pkg/__init__.py', stat.S_IREAD)
+    os.chmod('pkg/data.dat', stat.S_IREAD)
+    dist.parse_command_line()
+    dist.run_commands()
+    shutil.rmtree('build')
+
+
+@pytest.mark.xfail(
+    'platform.system() == "Windows"',
+    reason="On Windows, files do not have executable bits",
+    raises=AssertionError,
+    strict=True,
+)
+def test_executable_data(tmpdir_cwd):
+    """
+    Ensure executable bit is preserved in copy for
+    package data, as users rely on it for scripts.
+
+    #2041
+    """
+    dist = Distribution(dict(
+        script_name='setup.py',
+        script_args=['build_py'],
+        packages=['pkg'],
+        package_data={'pkg': ['run-me']},
+        name='pkg',
+    ))
+    os.makedirs('pkg')
+    open('pkg/__init__.py', 'w').close()
+    open('pkg/run-me', 'w').close()
+    os.chmod('pkg/run-me', 0o700)
+
+    dist.parse_command_line()
+    dist.run_commands()
+
+    assert os.stat('build/lib/pkg/run-me').st_mode & stat.S_IEXEC, \
+        "Script is not executable"
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 792975fd..bb89a865 100644
--- a/setuptools/tests/test_develop.py
+++ b/setuptools/tests/test_develop.py
@@ -17,6 +17,7 @@ import pytest
 
 from setuptools.command.develop import develop
 from setuptools.dist import Distribution
+from setuptools.tests import ack_2to3
 from . import contexts
 from . import namespaces
 
@@ -65,6 +66,7 @@ class TestDevelop:
     @pytest.mark.skipif(
         in_virtualenv or in_venv,
         reason="Cannot run when invoked in a virtualenv or venv")
+    @ack_2to3
     def test_2to3_user_mode(self, test_env):
         settings = dict(
             name='foo',
diff --git a/setuptools/tests/test_dist.py b/setuptools/tests/test_dist.py
index 36237f24..531ea1b4 100644
--- a/setuptools/tests/test_dist.py
+++ b/setuptools/tests/test_dist.py
@@ -5,12 +5,14 @@ from __future__ import unicode_literals
 import io
 import collections
 import re
+import functools
 from distutils.errors import DistutilsSetupError
 from setuptools.dist import (
     _get_unpatched,
     check_package_data,
     DistDeprecationWarning,
 )
+from setuptools import sic
 from setuptools import Distribution
 from setuptools.extern.six.moves.urllib.request import pathname2url
 from setuptools.extern.six.moves.urllib_parse import urljoin
@@ -61,7 +63,8 @@ def test_dist_fetch_build_egg(tmpdir):
             dist.fetch_build_egg(r)
             for r in reqs
         ]
-    assert [dist.key for dist in resolved_dists if dist] == reqs
+    # noqa below because on Python 2 it causes flakes
+    assert [dist.key for dist in resolved_dists if dist] == reqs  # noqa
 
 
 def test_dist__get_unpatched_deprecated():
@@ -69,75 +72,72 @@ def test_dist__get_unpatched_deprecated():
 
 
 def __read_test_cases():
-    # Metadata version 1.0
-    base_attrs = {
-        "name": "package",
-        "version": "0.0.1",
-        "author": "Foo Bar",
-        "author_email": "foo@bar.net",
-        "long_description": "Long\ndescription",
-        "description": "Short description",
-        "keywords": ["one", "two"]
-    }
-
-    def merge_dicts(d1, d2):
-        d1 = d1.copy()
-        d1.update(d2)
-
-        return d1
+    base = dict(
+        name="package",
+        version="0.0.1",
+        author="Foo Bar",
+        author_email="foo@bar.net",
+        long_description="Long\ndescription",
+        description="Short description",
+        keywords=["one", "two"],
+    )
+
+    params = functools.partial(dict, base)
 
     test_cases = [
-        ('Metadata version 1.0', base_attrs.copy()),
-        ('Metadata version 1.1: Provides', merge_dicts(base_attrs, {
-            'provides': ['package']
-        })),
-        ('Metadata version 1.1: Obsoletes', merge_dicts(base_attrs, {
-            'obsoletes': ['foo']
-        })),
-        ('Metadata version 1.1: Classifiers', merge_dicts(base_attrs, {
-            'classifiers': [
+        ('Metadata version 1.0', params()),
+        ('Metadata version 1.1: Provides', params(
+            provides=['package'],
+        )),
+        ('Metadata version 1.1: Obsoletes', params(
+            obsoletes=['foo'],
+        )),
+        ('Metadata version 1.1: Classifiers', params(
+            classifiers=[
                 'Programming Language :: Python :: 3',
                 'Programming Language :: Python :: 3.7',
                 'License :: OSI Approved :: MIT License',
-            ]})),
-        ('Metadata version 1.1: Download URL', merge_dicts(base_attrs, {
-            'download_url': 'https://example.com'
-        })),
-        ('Metadata Version 1.2: Requires-Python', merge_dicts(base_attrs, {
-            'python_requires': '>=3.7'
-        })),
+            ],
+        )),
+        ('Metadata version 1.1: Download URL', params(
+            download_url='https://example.com',
+        )),
+        ('Metadata Version 1.2: Requires-Python', params(
+            python_requires='>=3.7',
+        )),
         pytest.param(
             'Metadata Version 1.2: Project-Url',
-            merge_dicts(base_attrs, {
-                'project_urls': {
-                    'Foo': 'https://example.bar'
-                }
-            }), marks=pytest.mark.xfail(
-                reason="Issue #1578: project_urls not read"
-            )),
-        ('Metadata Version 2.1: Long Description Content Type',
-         merge_dicts(base_attrs, {
-             'long_description_content_type': 'text/x-rst; charset=UTF-8'
-         })),
+            params(project_urls=dict(Foo='https://example.bar')),
+            marks=pytest.mark.xfail(
+                reason="Issue #1578: project_urls not read",
+            ),
+        ),
+        ('Metadata Version 2.1: Long Description Content Type', params(
+            long_description_content_type='text/x-rst; charset=UTF-8',
+        )),
         pytest.param(
             'Metadata Version 2.1: Provides Extra',
-            merge_dicts(base_attrs, {
-                'provides_extras': ['foo', 'bar']
-            }), marks=pytest.mark.xfail(reason="provides_extras not read")),
-        ('Missing author, missing author e-mail',
-         {'name': 'foo', 'version': '1.0.0'}),
-        ('Missing author',
-         {'name': 'foo',
-          'version': '1.0.0',
-          'author_email': 'snorri@sturluson.name'}),
-        ('Missing author e-mail',
-         {'name': 'foo',
-          'version': '1.0.0',
-          'author': 'Snorri Sturluson'}),
-        ('Missing author',
-         {'name': 'foo',
-          'version': '1.0.0',
-          'author': 'Snorri Sturluson'}),
+            params(provides_extras=['foo', 'bar']),
+            marks=pytest.mark.xfail(reason="provides_extras not read"),
+        ),
+        ('Missing author', dict(
+            name='foo',
+            version='1.0.0',
+            author_email='snorri@sturluson.name',
+        )),
+        ('Missing author e-mail', dict(
+            name='foo',
+            version='1.0.0',
+            author='Snorri Sturluson',
+        )),
+        ('Missing author and e-mail', dict(
+            name='foo',
+            version='1.0.0',
+        )),
+        ('Bypass normalized version', dict(
+            name='foo',
+            version=sic('1.0.0a'),
+        )),
     ]
 
     return test_cases
@@ -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 2be1be47..3044cbd0 100644
--- a/setuptools/tests/test_easy_install.py
+++ b/setuptools/tests/test_easy_install.py
@@ -629,7 +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):
@@ -671,8 +671,10 @@ class TestSetupRequires:
                 dep_url = path_to_url(dep_sdist, authority='localhost')
                 test_pkg = create_setup_requires_package(
                     temp_dir,
-                    'python-xlib', '0.19', # Ignored (overriden by setup_attrs).
-                    setup_attrs=dict(setup_requires='dependency @ %s' % dep_url))
+                    # 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
@@ -710,11 +712,14 @@ class TestSetupRequires:
         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)
+        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)
+        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(
             '''
@@ -726,35 +731,41 @@ class TestSetupRequires:
                 <a href="{dep_2_0_url}" data-requires-python="{dep_2_0_python_requires}">{dep_2_0_sdist}</a><br/>
             </body>
             </html>
-            ''').format(
+            ''').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')
+        ), '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]))
+                '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'))))
+        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):
+    @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')
+                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')
@@ -771,7 +782,7 @@ class TestSetupRequires:
                             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,
+                        ''').format(use_legacy_installer=use_legacy_installer,  # noqa
                                     dependency_links=dependency_links))
                 with open(test_setup_cfg, 'w') as fp:
                     fp.write(DALS(
@@ -783,14 +794,17 @@ class TestSetupRequires:
                                     find_links=temp_dir))
                 run_setup(test_setup_py, [str('--version')])
 
-    def test_setup_requires_with_transitive_extra_dependency(self, monkeypatch):
+    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')
+                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)
@@ -806,12 +820,12 @@ class TestSetupRequires:
                     'setup.cfg': '',
                 }, prefix=dep_pkg)
                 # "Install" dep.
-                run_setup(os.path.join(dep_pkg, 'setup.py'), [str('dist_info')])
+                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')
-                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(
@@ -881,16 +895,19 @@ def make_nspkg_sdist(dist_path, distname, version):
 
 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', ''),
+        (
+            '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', ''),
     ])
 
 
@@ -948,16 +965,16 @@ def create_setup_requires_package(path, distname='foobar', version='0.1',
                 value = ';'.join(value)
             section.append('%s: %s' % (name, value))
         test_setup_cfg_contents = DALS(
-                """
-                [metadata]
-                {metadata}
-                [options]
-                {options}
-                """
-            ).format(
-                options='\n'.join(options),
-                metadata='\n'.join(metadata),
-            )
+            """
+            [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:
diff --git a/setuptools/tests/test_egg_info.py b/setuptools/tests/test_egg_info.py
index 0db204ba..109f9135 100644
--- a/setuptools/tests/test_egg_info.py
+++ b/setuptools/tests/test_egg_info.py
@@ -525,19 +525,19 @@ class TestEggInfo:
                               license_file = LICENSE
                               """),
             'LICENSE': "Test license"
-        }, True), # with license
+        }, True),  # with license
         ({
             'setup.cfg': DALS("""
                               [metadata]
                               license_file = INVALID_LICENSE
                               """),
             'LICENSE': "Test license"
-        }, False), # with an invalid license
+        }, False),  # with an invalid license
         ({
             'setup.cfg': DALS("""
                               """),
             'LICENSE': "Test license"
-        }, False), # no license_file attribute
+        }, False),  # no license_file attribute
         ({
             'setup.cfg': DALS("""
                               [metadata]
@@ -545,7 +545,7 @@ class TestEggInfo:
                               """),
             'MANIFEST.in': "exclude LICENSE",
             'LICENSE': "Test license"
-        }, False) # license file is manually excluded
+        }, False)  # license file is manually excluded
     ])
     def test_setup_cfg_license_file(
             self, tmpdir_cwd, env, files, license_in_sources):
@@ -565,7 +565,8 @@ 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", [
         ({
@@ -577,7 +578,7 @@ class TestEggInfo:
                               """),
             'LICENSE-ABC': "ABC license",
             'LICENSE-XYZ': "XYZ license"
-        }, ['LICENSE-ABC', 'LICENSE-XYZ'], []), # with licenses
+        }, ['LICENSE-ABC', 'LICENSE-XYZ'], []),  # with licenses
         ({
             'setup.cfg': DALS("""
                               [metadata]
@@ -585,7 +586,7 @@ class TestEggInfo:
                               """),
             'LICENSE-ABC': "ABC license",
             'LICENSE-XYZ': "XYZ license"
-        }, ['LICENSE-ABC', 'LICENSE-XYZ'], []), # with commas
+        }, ['LICENSE-ABC', 'LICENSE-XYZ'], []),  # with commas
         ({
             'setup.cfg': DALS("""
                               [metadata]
@@ -594,7 +595,7 @@ class TestEggInfo:
                               """),
             'LICENSE-ABC': "ABC license",
             'LICENSE-XYZ': "XYZ license"
-        }, ['LICENSE-ABC'], ['LICENSE-XYZ']), # with one license
+        }, ['LICENSE-ABC'], ['LICENSE-XYZ']),  # with one license
         ({
             'setup.cfg': DALS("""
                               [metadata]
@@ -602,7 +603,7 @@ class TestEggInfo:
                               """),
             'LICENSE-ABC': "ABC license",
             'LICENSE-XYZ': "XYZ license"
-        }, [], ['LICENSE-ABC', 'LICENSE-XYZ']), # empty
+        }, [], ['LICENSE-ABC', 'LICENSE-XYZ']),  # empty
         ({
             'setup.cfg': DALS("""
                               [metadata]
@@ -610,7 +611,7 @@ class TestEggInfo:
                               """),
             'LICENSE-ABC': "ABC license",
             'LICENSE-XYZ': "XYZ license"
-        }, ['LICENSE-XYZ'], ['LICENSE-ABC']), # on same line
+        }, ['LICENSE-XYZ'], ['LICENSE-ABC']),  # on same line
         ({
             'setup.cfg': DALS("""
                               [metadata]
@@ -619,12 +620,12 @@ class TestEggInfo:
                                   INVALID_LICENSE
                               """),
             'LICENSE-ABC': "Test license"
-        }, ['LICENSE-ABC'], ['INVALID_LICENSE']), # with an invalid license
+        }, ['LICENSE-ABC'], ['INVALID_LICENSE']),  # with an invalid license
         ({
             'setup.cfg': DALS("""
                               """),
             'LICENSE': "Test license"
-        }, [], ['LICENSE']), # no license_files attribute
+        }, [], ['LICENSE']),  # no license_files attribute
         ({
             'setup.cfg': DALS("""
                               [metadata]
@@ -632,7 +633,7 @@ class TestEggInfo:
                               """),
             'MANIFEST.in': "exclude LICENSE",
             'LICENSE': "Test license"
-        }, [], ['LICENSE']), # license file is manually excluded
+        }, [], ['LICENSE']),  # license file is manually excluded
         ({
             'setup.cfg': DALS("""
                               [metadata]
@@ -643,7 +644,7 @@ class TestEggInfo:
             'MANIFEST.in': "exclude LICENSE-XYZ",
             'LICENSE-ABC': "ABC license",
             'LICENSE-XYZ': "XYZ license"
-        }, ['LICENSE-ABC'], ['LICENSE-XYZ']) # subset is manually excluded
+        }, ['LICENSE-ABC'], ['LICENSE-XYZ'])  # subset is manually excluded
     ])
     def test_setup_cfg_license_files(
             self, tmpdir_cwd, env, files, incl_licenses, excl_licenses):
@@ -674,7 +675,7 @@ class TestEggInfo:
                               """),
             'LICENSE-ABC': "ABC license",
             'LICENSE-XYZ': "XYZ license"
-        }, [], ['LICENSE-ABC', 'LICENSE-XYZ']), # both empty
+        }, [], ['LICENSE-ABC', 'LICENSE-XYZ']),  # both empty
         ({
             'setup.cfg': DALS("""
                               [metadata]
@@ -684,7 +685,8 @@ class TestEggInfo:
                               """),
             'LICENSE-ABC': "ABC license",
             'LICENSE-XYZ': "XYZ license"
-        }, [], ['LICENSE-ABC', 'LICENSE-XYZ']), # license_file is still singular
+            # license_file is still singular
+        }, [], ['LICENSE-ABC', 'LICENSE-XYZ']),
         ({
             'setup.cfg': DALS("""
                               [metadata]
@@ -696,7 +698,7 @@ class TestEggInfo:
             'LICENSE-ABC': "ABC license",
             'LICENSE-PQR': "PQR license",
             'LICENSE-XYZ': "XYZ license"
-        }, ['LICENSE-ABC', 'LICENSE-PQR', 'LICENSE-XYZ'], []), # combined
+        }, ['LICENSE-ABC', 'LICENSE-PQR', 'LICENSE-XYZ'], []),  # combined
         ({
             'setup.cfg': DALS("""
                               [metadata]
@@ -709,7 +711,8 @@ class TestEggInfo:
             'LICENSE-ABC': "ABC license",
             'LICENSE-PQR': "PQR license",
             'LICENSE-XYZ': "XYZ license"
-        }, ['LICENSE-ABC', 'LICENSE-PQR', 'LICENSE-XYZ'], []), # duplicate license
+            # duplicate license
+        }, ['LICENSE-ABC', 'LICENSE-PQR', 'LICENSE-XYZ'], []),
         ({
             'setup.cfg': DALS("""
                               [metadata]
@@ -720,7 +723,8 @@ class TestEggInfo:
             'LICENSE-ABC': "ABC license",
             'LICENSE-PQR': "PQR license",
             'LICENSE-XYZ': "XYZ license"
-        }, ['LICENSE-ABC', 'LICENSE-XYZ'], ['LICENSE-PQR']), # combined subset
+            # combined subset
+        }, ['LICENSE-ABC', 'LICENSE-XYZ'], ['LICENSE-PQR']),
         ({
             'setup.cfg': DALS("""
                               [metadata]
@@ -730,7 +734,8 @@ class TestEggInfo:
                                   LICENSE-PQR
                               """),
             'LICENSE-PQR': "Test license"
-        }, ['LICENSE-PQR'], ['LICENSE-ABC', 'LICENSE-XYZ']), # with invalid licenses
+            # with invalid licenses
+        }, ['LICENSE-PQR'], ['LICENSE-ABC', 'LICENSE-XYZ']),
         ({
             'setup.cfg': DALS("""
                               [metadata]
@@ -743,7 +748,8 @@ class TestEggInfo:
             'LICENSE-ABC': "ABC license",
             'LICENSE-PQR': "PQR license",
             'LICENSE-XYZ': "XYZ license"
-        }, ['LICENSE-XYZ'], ['LICENSE-ABC', 'LICENSE-PQR']) # manually excluded
+            # 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):
diff --git a/setuptools/tests/test_extern.py b/setuptools/tests/test_extern.py
new file mode 100644
index 00000000..3519a680
--- /dev/null
+++ b/setuptools/tests/test_extern.py
@@ -0,0 +1,22 @@
+import importlib
+import pickle
+
+from setuptools import Distribution
+from setuptools.extern import ordered_set
+from setuptools.tests import py3_only
+
+
+def test_reimport_extern():
+    ordered_set2 = importlib.import_module(ordered_set.__name__)
+    assert ordered_set is ordered_set2
+
+
+def test_orderedset_pickle_roundtrip():
+    o1 = ordered_set.OrderedSet([1, 2, 5])
+    o2 = pickle.loads(pickle.dumps(o1))
+    assert o1 == o2
+
+
+@py3_only
+def test_distribution_picklable():
+    pickle.loads(pickle.dumps(Distribution()))
diff --git a/setuptools/tests/test_msvc14.py b/setuptools/tests/test_msvc14.py
new file mode 100644
index 00000000..7833aab4
--- /dev/null
+++ b/setuptools/tests/test_msvc14.py
@@ -0,0 +1,84 @@
+# -*- coding: utf-8 -*-
+"""
+Tests for msvc support module (msvc14 unit tests).
+"""
+
+import os
+from distutils.errors import DistutilsPlatformError
+import pytest
+import sys
+
+
+@pytest.mark.skipif(sys.platform != "win32",
+                    reason="These tests are only for win32")
+class TestMSVC14:
+    """Python 3.8 "distutils/tests/test_msvccompiler.py" backport"""
+    def test_no_compiler(self):
+        import setuptools.msvc as _msvccompiler
+        # makes sure query_vcvarsall raises
+        # a DistutilsPlatformError if the compiler
+        # is not found
+
+        def _find_vcvarsall(plat_spec):
+            return None, None
+
+        old_find_vcvarsall = _msvccompiler._msvc14_find_vcvarsall
+        _msvccompiler._msvc14_find_vcvarsall = _find_vcvarsall
+        try:
+            pytest.raises(DistutilsPlatformError,
+                          _msvccompiler._msvc14_get_vc_env,
+                          'wont find this version')
+        finally:
+            _msvccompiler._msvc14_find_vcvarsall = old_find_vcvarsall
+
+    @pytest.mark.skipif(sys.version_info[0] < 3,
+                        reason="Unicode requires encode/decode on Python 2")
+    def test_get_vc_env_unicode(self):
+        import setuptools.msvc as _msvccompiler
+
+        test_var = 'ṰḖṤṪ┅ṼẨṜ'
+        test_value = '₃⁴₅'
+
+        # Ensure we don't early exit from _get_vc_env
+        old_distutils_use_sdk = os.environ.pop('DISTUTILS_USE_SDK', None)
+        os.environ[test_var] = test_value
+        try:
+            env = _msvccompiler._msvc14_get_vc_env('x86')
+            assert test_var.lower() in env
+            assert test_value == env[test_var.lower()]
+        finally:
+            os.environ.pop(test_var)
+            if old_distutils_use_sdk:
+                os.environ['DISTUTILS_USE_SDK'] = old_distutils_use_sdk
+
+    def test_get_vc2017(self):
+        import setuptools.msvc as _msvccompiler
+
+        # This function cannot be mocked, so pass it if we find VS 2017
+        # and mark it skipped if we do not.
+        version, path = _msvccompiler._msvc14_find_vc2017()
+        if os.environ.get('APPVEYOR_BUILD_WORKER_IMAGE', '') in [
+            'Visual Studio 2017'
+        ]:
+            assert version
+        if version:
+            assert version >= 15
+            assert os.path.isdir(path)
+        else:
+            pytest.skip("VS 2017 is not installed")
+
+    def test_get_vc2015(self):
+        import setuptools.msvc as _msvccompiler
+
+        # This function cannot be mocked, so pass it if we find VS 2015
+        # and mark it skipped if we do not.
+        version, path = _msvccompiler._msvc14_find_vc2015()
+        if os.environ.get('APPVEYOR_BUILD_WORKER_IMAGE', '') in [
+            'Visual Studio 2015', 'Visual Studio 2017'
+        ]:
+            assert version
+        if version:
+            assert version >= 14
+            assert os.path.isdir(path)
+        else:
+            pytest.skip("VS 2015 is not installed")
diff --git a/setuptools/tests/test_packageindex.py b/setuptools/tests/test_packageindex.py
index 60d968fd..29aace13 100644
--- a/setuptools/tests/test_packageindex.py
+++ b/setuptools/tests/test_packageindex.py
@@ -3,15 +3,14 @@ from __future__ import absolute_import
 import sys
 import os
 import distutils.errors
+import platform
 
 from setuptools.extern import six
 from setuptools.extern.six.moves import urllib, http_client
 import mock
 import pytest
 
-import pkg_resources
 import setuptools.package_index
-from setuptools.tests.server import IndexServer
 from .textwrap import DALS
 
 
@@ -114,43 +113,6 @@ class TestPackageIndex:
         url = 'file:///tmp/test_package_index'
         assert index.url_ok(url, True)
 
-    def test_links_priority(self):
-        """
-        Download links from the pypi simple index should be used before
-        external download links.
-        https://bitbucket.org/tarek/distribute/issue/163
-
-        Usecase :
-        - someone uploads a package on pypi, a md5 is generated
-        - someone manually copies this link (with the md5 in the url) onto an
-          external page accessible from the package page.
-        - someone reuploads the package (with a different md5)
-        - while easy_installing, an MD5 error occurs because the external link
-          is used
-        -> Setuptools should use the link from pypi, not the external one.
-        """
-        if sys.platform.startswith('java'):
-            # Skip this test on jython because binding to :0 fails
-            return
-
-        # start an index server
-        server = IndexServer()
-        server.start()
-        index_url = server.base_url() + 'test_links_priority/simple/'
-
-        # scan a test index
-        pi = setuptools.package_index.PackageIndex(index_url)
-        requirement = pkg_resources.Requirement.parse('foobar')
-        pi.find_packages(requirement)
-        server.stop()
-
-        # the distribution has been found
-        assert 'foobar' in pi
-        # we have only one link, because links are compared without md5
-        assert len(pi['foobar']) == 1
-        # the link should be from the index
-        assert 'correct_md5' in pi['foobar'][0].location
-
     def test_parse_bdist_wininst(self):
         parse = setuptools.package_index.parse_bdist_wininst
 
@@ -221,11 +183,11 @@ class TestPackageIndex:
             ('+ubuntu_0', '+ubuntu.0'),
         ]
         versions = [
-            [''.join([e, r, p, l]) for l in ll]
+            [''.join([e, r, p, loc]) for loc in locs]
             for e in epoch
             for r in releases
             for p in sum([pre, post, dev], [''])
-            for ll in local]
+            for locs in local]
         for v, vc in versions:
             dists = list(setuptools.package_index.distros_for_url(
                 'http://example.com/example.zip#egg=example-' + v))
@@ -322,17 +284,27 @@ class TestContentCheckers:
         assert rep == 'My message about md5'
 
 
+@pytest.fixture
+def temp_home(tmpdir, monkeypatch):
+    key = (
+        'USERPROFILE'
+        if platform.system() == 'Windows' and sys.version_info > (3, 8) else
+        'HOME'
+    )
+
+    monkeypatch.setitem(os.environ, key, str(tmpdir))
+    return tmpdir
+
+
 class TestPyPIConfig:
-    def test_percent_in_password(self, tmpdir, monkeypatch):
-        monkeypatch.setitem(os.environ, 'HOME', str(tmpdir))
-        pypirc = tmpdir / '.pypirc'
-        with pypirc.open('w') as strm:
-            strm.write(DALS("""
-                [pypi]
-                repository=https://pypi.org
-                username=jaraco
-                password=pity%
-            """))
+    def test_percent_in_password(self, temp_home):
+        pypirc = temp_home / '.pypirc'
+        pypirc.write(DALS("""
+            [pypi]
+            repository=https://pypi.org
+            username=jaraco
+            password=pity%
+        """))
         cfg = setuptools.package_index.PyPIConfig()
         cred = cfg.creds_by_repository['https://pypi.org']
         assert cred.username == 'jaraco'
diff --git a/setuptools/tests/test_setuptools.py b/setuptools/tests/test_setuptools.py
index 5896a69a..08d263ae 100644
--- a/setuptools/tests/test_setuptools.py
+++ b/setuptools/tests/test_setuptools.py
@@ -4,7 +4,7 @@ import sys
 import os
 import distutils.core
 import distutils.cmd
-from distutils.errors import DistutilsOptionError, DistutilsPlatformError
+from distutils.errors import DistutilsOptionError
 from distutils.errors import DistutilsSetupError
 from distutils.core import Extension
 from distutils.version import LooseVersion
@@ -14,7 +14,6 @@ import pytest
 import setuptools
 import setuptools.dist
 import setuptools.depends as dep
-from setuptools import Feature
 from setuptools.depends import Require
 from setuptools.extern import six
 
@@ -108,6 +107,11 @@ class TestDepends:
         assert not req.is_present()
         assert not req.is_current()
 
+    @needs_bytecode
+    def test_require_present(self):
+        # In #1896, this test was failing for months with the only
+        # complaint coming from test runners (not end users).
+        # TODO: Evaluate if this code is needed at all.
         req = Require('Tests', None, 'tests', homepage="http://example.com")
         assert req.format is None
         assert req.attribute is None
@@ -211,86 +215,6 @@ class TestDistro:
             self.dist.exclude(package_dir=['q'])
 
 
-@pytest.mark.filterwarnings('ignore:Features are deprecated')
-class TestFeatures:
-    def setup_method(self, method):
-        self.req = Require('Distutils', '1.0.3', 'distutils')
-        self.dist = makeSetup(
-            features={
-                'foo': Feature(
-                    "foo", standard=True, require_features=['baz', self.req]),
-                'bar': Feature("bar", standard=True, packages=['pkg.bar'],
-                               py_modules=['bar_et'], remove=['bar.ext'],
-                               ),
-                'baz': Feature(
-                        "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'],
-            packages=['pkg.bar', 'pkg.foo'],
-            py_modules=['bar_et', 'bazish'],
-            ext_modules=[Extension('bar.ext', ['bar.c'])]
-        )
-
-    def testDefaults(self):
-        assert not Feature(
-            "test", standard=True, remove='x', available=False
-        ).include_by_default()
-        assert Feature("test", standard=True, remove='x').include_by_default()
-        # Feature must have either kwargs, removes, or require_features
-        with pytest.raises(DistutilsSetupError):
-            Feature("test")
-
-    def testAvailability(self):
-        with pytest.raises(DistutilsPlatformError):
-            self.dist.features['dwim'].include_in(self.dist)
-
-    def testFeatureOptions(self):
-        dist = self.dist
-        assert (
-            ('with-dwim', None, 'include DWIM') in dist.feature_options
-        )
-        assert (
-            ('without-dwim', None, 'exclude DWIM (default)')
-            in dist.feature_options
-        )
-        assert (
-            ('with-bar', None, 'include bar (default)') in dist.feature_options
-        )
-        assert (
-            ('without-bar', None, 'exclude bar') in dist.feature_options
-        )
-        assert dist.feature_negopt['without-foo'] == 'with-foo'
-        assert dist.feature_negopt['without-bar'] == 'with-bar'
-        assert dist.feature_negopt['without-dwim'] == 'with-dwim'
-        assert ('without-baz' not in dist.feature_negopt)
-
-    def testUseFeatures(self):
-        dist = self.dist
-        assert dist.with_foo == 1
-        assert dist.with_bar == 0
-        assert dist.with_baz == 1
-        assert ('bar_et' not in dist.py_modules)
-        assert ('pkg.bar' not in dist.packages)
-        assert ('pkg.baz' in dist.packages)
-        assert ('scripts/baz_it' in dist.scripts)
-        assert (('libfoo', 'foo/foofoo.c') in dist.libraries)
-        assert dist.ext_modules == []
-        assert dist.require_features == [self.req]
-
-        # If we ask for bar, it should fail because we explicitly disabled
-        # it on the command line
-        with pytest.raises(DistutilsOptionError):
-            dist.include_feature('bar')
-
-    def testFeatureWithInvalidRemove(self):
-        with pytest.raises(SystemExit):
-            makeSetup(features={'x': Feature('x', remove='y')})
-
-
 class TestCommandTests:
     def testTestIsCommand(self):
         test_cmd = makeSetup().get_command_obj('test')
diff --git a/setuptools/tests/test_test.py b/setuptools/tests/test_test.py
index 6242a018..892fd120 100644
--- a/setuptools/tests/test_test.py
+++ b/setuptools/tests/test_test.py
@@ -10,9 +10,10 @@ import pytest
 
 from setuptools.command.test import test
 from setuptools.dist import Distribution
+from setuptools.tests import ack_2to3
 
 from .textwrap import DALS
-from . import contexts
+
 
 SETUP_PY = DALS("""
     from setuptools import setup
@@ -74,6 +75,7 @@ def quiet_log():
 
 
 @pytest.mark.usefixtures('sample_test', 'quiet_log')
+@ack_2to3
 def test_test(capfd):
     params = dict(
         name='foo',
@@ -124,6 +126,7 @@ def test_tests_are_run_once(capfd):
 
 
 @pytest.mark.usefixtures('sample_test')
+@ack_2to3
 def test_warns_deprecation(capfd):
     params = dict(
         name='foo',
@@ -149,6 +152,7 @@ def test_warns_deprecation(capfd):
 
 
 @pytest.mark.usefixtures('sample_test')
+@ack_2to3
 def test_deprecation_stderr(capfd):
     params = dict(
         name='foo',
diff --git a/setuptools/tests/test_virtualenv.py b/setuptools/tests/test_virtualenv.py
index 2c35825a..555273ae 100644
--- a/setuptools/tests/test_virtualenv.py
+++ b/setuptools/tests/test_virtualenv.py
@@ -8,13 +8,22 @@ 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
 
 
 @pytest.fixture(autouse=True)
+def disable_requires_python(monkeypatch):
+    """
+    Disable Requires-Python on Python 2.7
+    """
+    if sys.version_info > (3,):
+        return
+
+    monkeypatch.setenv('PIP_IGNORE_REQUIRES_PYTHON', 'true')
+
+
+@pytest.fixture(autouse=True)
 def pytest_virtualenv_works(virtualenv):
     """
     pytest_virtualenv may not work. if it doesn't, skip these
@@ -48,10 +57,7 @@ def test_clean_env_install(bare_virtualenv):
     """
     Check setuptools can be installed in a clean environment.
     """
-    bare_virtualenv.run(' && '.join((
-        'cd {source}',
-        'python setup.py install',
-    )).format(source=SOURCE_DIR))
+    bare_virtualenv.run(['python', 'setup.py', 'install'], cd=SOURCE_DIR)
 
 
 def _get_pip_versions():
@@ -64,7 +70,7 @@ 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)
@@ -106,10 +112,9 @@ def test_pip_upgrade_from_source(pip_version, virtualenv):
     dist_dir = virtualenv.workspace
     # Generate source distribution / wheel.
     virtualenv.run(' && '.join((
-        'cd {source}',
         'python setup.py -q sdist -d {dist}',
         'python setup.py -q bdist_wheel -d {dist}',
-    )).format(source=SOURCE_DIR, dist=dist_dir))
+    )).format(dist=dist_dir), cd=SOURCE_DIR)
     sdist = glob.glob(os.path.join(dist_dir, '*.zip'))[0]
     wheel = glob.glob(os.path.join(dist_dir, '*.whl'))[0]
     # Then update from wheel.
@@ -174,18 +179,20 @@ def _check_test_command_install_requirements(virtualenv, tmpdir):
             open('success', 'w').close()
             '''))
     # Run test command for test package.
-    virtualenv.run(' && '.join((
-        'cd {tmpdir}',
-        'python setup.py test -s test',
-    )).format(tmpdir=tmpdir))
+    virtualenv.run(
+        ['python', 'setup.py', 'test', '-s', 'test'], cd=str(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'])\"")
+    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):
+
+def test_test_command_install_requirements_when_using_easy_install(
+        bare_virtualenv, tmpdir):
     _check_test_command_install_requirements(bare_virtualenv, tmpdir)
 
 
@@ -194,7 +201,5 @@ def test_no_missing_dependencies(bare_virtualenv):
     Quick and dirty test to ensure all external dependencies are vendored.
     """
     for command in ('upload',):  # sorted(distutils.command.__all__):
-        bare_virtualenv.run(' && '.join((
-            'cd {source}',
-            'python setup.py {command} -h',
-        )).format(command=command, source=SOURCE_DIR))
+        bare_virtualenv.run(
+            ['python', 'setup.py', command, '-h'], cd=SOURCE_DIR)
diff --git a/setuptools/tests/test_wheel.py b/setuptools/tests/test_wheel.py
index 55d346c6..f72ccbbf 100644
--- a/setuptools/tests/test_wheel.py
+++ b/setuptools/tests/test_wheel.py
@@ -125,11 +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,
@@ -455,7 +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(
@@ -579,4 +581,5 @@ def test_wheel_is_compatible(monkeypatch):
         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()
+    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 025aaa82..ec1106a7 100644
--- a/setuptools/wheel.py
+++ b/setuptools/wheel.py
@@ -77,7 +77,8 @@ class Wheel:
 
     def is_compatible(self):
         '''Is the wheel is compatible with the current platform?'''
-        supported_tags = set((t.interpreter, t.abi, t.platform) for t in sys_tags())
+        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/tools/finalize.py b/tools/finalize.py
new file mode 100644
index 00000000..98b06c07
--- /dev/null
+++ b/tools/finalize.py
@@ -0,0 +1,81 @@
+"""
+Finalize the repo for a release. Invokes towncrier and bumpversion.
+"""
+
+__requires__ = ['bump2version', 'towncrier']
+
+
+import subprocess
+import pathlib
+import re
+import sys
+
+
+def release_kind():
+    """
+    Determine which release to make based on the files in the
+    changelog.
+    """
+    # use min here as 'major' < 'minor' < 'patch'
+    return min(
+        'major' if 'breaking' in file.name else
+        'minor' if 'change' in file.name else
+        'patch'
+        for file in pathlib.Path('changelog.d').iterdir()
+    )
+
+
+bump_version_command = [
+    sys.executable,
+    '-m', 'bumpversion',
+    release_kind(),
+]
+
+
+def get_version():
+    cmd = bump_version_command + ['--dry-run', '--verbose']
+    out = subprocess.check_output(cmd, text=True)
+    return re.search('^new_version=(.*)', out, re.MULTILINE).group(1)
+
+
+def update_changelog():
+    cmd = [
+        sys.executable, '-m',
+        'towncrier',
+        '--version', get_version(),
+        '--yes',
+    ]
+    subprocess.check_call(cmd)
+
+
+def bump_version():
+    cmd = bump_version_command + ['--allow-dirty']
+    subprocess.check_call(cmd)
+
+
+def ensure_config():
+    """
+    Double-check that Git has an e-mail configured.
+    """
+    subprocess.check_output(['git', 'config', 'user.email'])
+
+
+def check_changes():
+    """
+    Verify that all of the files in changelog.d have the appropriate
+    names.
+    """
+    allowed = 'deprecation', 'breaking', 'change', 'doc', 'misc'
+    assert all(
+        any(key in file.name for key in allowed)
+        for file in pathlib.Path('changelog.d').iterdir()
+        if file.name != '.gitignore'
+    )
+
+
+if __name__ == '__main__':
+    print("Cutting release at", get_version())
+    ensure_config()
+    check_changes()
+    update_changelog()
+    bump_version()
diff --git a/tools/tox_pip.py b/tools/tox_pip.py
index 06655fe4..9fe4f905 100644
--- a/tools/tox_pip.py
+++ b/tools/tox_pip.py
@@ -1,6 +1,7 @@
 import os
 import subprocess
 import sys
+import re
 
 
 def remove_setuptools():
@@ -14,17 +15,68 @@ def remove_setuptools():
     subprocess.check_call(cmd, cwd='.tox')
 
 
-def 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'
+def bootstrap():
+    print("Running bootstrap")
+    cmd = [sys.executable, '-m', 'bootstrap']
+    subprocess.check_call(cmd)
 
-    # When installing '.', remove setuptools
-    '.' in args and remove_setuptools()
 
-    cmd = [sys.executable, '-m', 'pip'] + args
-    subprocess.check_call(cmd)
+def is_install_self(args):
+    """
+    Do the args represent an install of .?
+    """
+    def strip_extras(arg):
+        match = re.match(r'(.*)?\[.*\]$', arg)
+        return match.group(1) if match else arg
+
+    return (
+        'install' in args
+        and any(
+            arg in ['.', os.getcwd()]
+            for arg in map(strip_extras, args)
+        )
+    )
+
+
+def pip(*args):
+    cmd = [sys.executable, '-m', 'pip'] + list(args)
+    return subprocess.check_call(cmd)
+
+
+def test_dependencies():
+    from ConfigParser import ConfigParser
+
+    def clean(dep):
+        spec, _, _ = dep.partition('#')
+        return spec.strip()
+
+    parser = ConfigParser()
+    parser.read('setup.cfg')
+    raw = parser.get('options.extras_require', 'tests').split('\n')
+    return filter(None, map(clean, raw))
+
+
+def disable_python_requires():
+    """
+    On Python 2, install the dependencies that are selective
+    on Python version while honoring REQUIRES_PYTHON, then
+    disable REQUIRES_PYTHON so that pip can install this
+    checkout of setuptools.
+    """
+    pip('install', *test_dependencies())
+    os.environ['PIP_IGNORE_REQUIRES_PYTHON'] = 'true'
+
+
+def run(args):
+    os.environ['PIP_USE_PEP517'] = 'true'
+
+    if is_install_self(args):
+        remove_setuptools()
+        bootstrap()
+        sys.version_info > (3,) or disable_python_requires()
+
+    pip(*args)
 
 
 if __name__ == '__main__':
-    pip(sys.argv[1:])
+    run(sys.argv[1:])
diff --git a/tox.ini b/tox.ini
index d458dc33..aa99e283 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,32 +1,32 @@
-# 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{5,6,7,8},pypy,pypy3'
+# export TOXENV='py3{5,6,7,8},pypy,pypy3'
 
 [tox]
 envlist=python
 minversion = 3.2
 requires =
 	tox-pip-version >= 0.0.6
+	# workaround for #1998
+	virtualenv < 20
 
 [helpers]
 # Custom pip behavior
 pip = python {toxinidir}/tools/tox_pip.py
 
 [testenv]
-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}
-	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
+passenv=APPDATA HOMEDRIVE HOMEPATH windir Program* CommonProgram* VS* APPVEYOR APPVEYOR_* CI CODECOV_* TRAVIS TRAVIS_* NETWORK_REQUIRED
 commands=pytest --cov-config={toxinidir}/tox.ini --cov-report= {posargs}
 usedevelop=True
+extras =
+	tests
 
 
 [testenv:coverage]
@@ -46,12 +46,12 @@ skip_install=True
 commands=codecov -X gcov --file {toxworkdir}/coverage.xml
 
 [testenv:docs]
-deps = -r{toxinidir}/docs/requirements.txt
-skip_install=True
+extras =
+        docs
+        testing
+changedir = docs
 commands =
-    python {toxinidir}/bootstrap.py
-    sphinx-build -W -b html -d {envtmpdir}/doctrees docs docs/build/html
-    sphinx-build -W -b man -d {envtmpdir}/doctrees docs docs/build/man
+        python -m sphinx . {toxinidir}/build/html
 
 [coverage:run]
 source=
@@ -60,6 +60,15 @@ source=
 omit=
 	*/_vendor/*
 
+[testenv:finalize]
+skip_install = True
+deps =
+	towncrier
+	bump2version
+passenv = *
+commands =
+	python tools/finalize.py
+
 [testenv:release]
 skip_install = True
 deps =