Use PY3/PY2 indicators to reliably select behavior. Fixes #237

--HG--
extra : amend_source : 33f3d298acd39933ccf60810902feb2a5d51c793

2 files changed, 17 insertions, 8 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index 83b05bbe..185052fb 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -3,6 +3,14 @@ CHANGES
 =======
 
 ---
+5.8
+---
+
+* Issue #237: ``pkg_resources`` now uses explicit detection of Python 2 vs.
+  Python 3, supporting environments where builtins have been patched to make
+  Python 3 look more like Python 2.
+
+---
 5.7
 ---
 
diff --git a/pkg_resources.py b/pkg_resources.py
index a0566688..5dcfd66e 100644
--- a/pkg_resources.py
+++ b/pkg_resources.py
@@ -38,16 +38,13 @@ from pkgutil import get_importer
 PY3 = sys.version_info > (3,)
 PY2 = not PY3
 
-try:
-    from urlparse import urlparse, urlunparse
-except ImportError:
+if PY3:
     from urllib.parse import urlparse, urlunparse
 
-try:
-    basestring
-    next = lambda o: o.next()
-    from cStringIO import StringIO as BytesIO
-except NameError:
+if PY2:
+    from urlparse import urlparse, urlunparse
+
+if PY3:
     basestring = str
     from io import BytesIO
     def execfile(fn, globs=None, locs=None):
@@ -57,6 +54,10 @@ except NameError:
             locs = globs
         exec(compile(open(fn).read(), fn, 'exec'), globs, locs)
 
+if PY2:
+    next = lambda o: o.next()
+    from cStringIO import StringIO as BytesIO
+
 # capture these to bypass sandboxing
 from os import utime
 try: