Setuptools now uses the 'packaging' package from pkg_resources, unifying the behavior around resolution of that package.

Author: jaraco

pkg_resources/__init__.py

@@ -75,9 +75,14 @@
 except ImportError:
     pass
 
-import pkg_resources._vendor.packaging.version
-import pkg_resources._vendor.packaging.specifiers
-packaging = pkg_resources._vendor.packaging
+try:
+    import packaging.version
+    import packaging.specifiers
+except ImportError:
+    # fallback to vendored version
+    import pkg_resources._vendor.packaging.version
+    import pkg_resources._vendor.packaging.specifiers
+    packaging = pkg_resources._vendor.packaging
 
 
 class PEP440Warning(RuntimeWarning):

setuptools/command/egg_info.py

@@ -11,13 +11,6 @@
 import re
 import sys
 
-try:
-    import packaging.version
-except ImportError:
-    # fallback to vendored version
-    import pkg_resources._vendor.packaging.version
-    packaging = pkg_resources._vendor.packaging
-
 from setuptools import Command
 from setuptools.command.sdist import sdist
 from setuptools.compat import basestring, PY3, StringIO
@@ -28,6 +21,7 @@
     safe_version, yield_lines, EntryPoint, iter_entry_points, to_filename)
 import setuptools.unicode_utils as unicode_utils
 
+from pkg_resources import packaging
 
 class egg_info(Command):
     description = "create a distribution's .egg-info directory"

setuptools/dist.py

@@ -13,18 +13,13 @@
 from distutils.errors import (DistutilsOptionError, DistutilsPlatformError,
     DistutilsSetupError)
 
-try:
-    import packaging.version
-except ImportError:
-    # fallback to vendored version
-    import pkg_resources._vendor.packaging.version
-    packaging = pkg_resources._vendor.packaging
-
 from setuptools.depends import Require
 from setuptools.compat import basestring, PY2
 from setuptools import windows_support
 import pkg_resources
 
+packaging = pkg_resources.packaging
+
 
 def _get_unpatched(cls):
     """Protect against re-patching the distutils if reloaded

setuptools/tests/test_resources.py

@@ -8,15 +8,13 @@
 import shutil
 from unittest import TestCase
 
-import pkg_resources._vendor.packaging.version
-import pkg_resources._vendor.packaging.specifiers
-packaging = pkg_resources._vendor.packaging
-
 import pkg_resources
 from pkg_resources import (parse_requirements, VersionConflict, parse_version,
     Distribution, EntryPoint, Requirement, safe_version, safe_name,
     WorkingSet)
 
+packaging = pkg_resources.packaging
+
 from setuptools.command.easy_install import (get_script_header, is_sh,
     nt_quote_arg)
 from setuptools.compat import StringIO, iteritems, PY3