Merge pull request #2247 from pypa/distutils-adopt-escape-hatch

Re-enable distutils adoption with escape hatch

Author: jaraco

changelog.d/2232.misc.patch

@@ -0,0 +1 @@
+In preparation for re-enabling a local copy of distutils, Setuptools now honors an environment variable, SETUPTOOLS_USE_DISTUTILS. If set to 'stdlib' (current default), distutils will be used from the standard library. If set to 'local' (default in a imminent backward-incompatible release), the local copy of distutils will be used.

setuptools/__init__.py

@@ -4,7 +4,7 @@
 import functools
 
 # Disabled for now due to: #2228, #2230
-# import setuptools.distutils_patch  # noqa: F401
+import setuptools.distutils_patch  # noqa: F401
 
 import distutils.core
 import distutils.filelist

setuptools/distutils_patch.py

@@ -7,6 +7,7 @@
 
 import sys
 import re
+import os
 import importlib
 import warnings
 
@@ -20,6 +21,14 @@ def clear_distutils():
         del sys.modules[name]
 
 
+def enabled():
+    """
+    Allow selection of distutils by environment variable.
+    """
+    which = os.environ.get('SETUPTOOLS_USE_DISTUTILS', 'stdlib')
+    return which == 'local'
+
+
 def ensure_local_distutils():
     clear_distutils()
     distutils = importlib.import_module('setuptools._distutils')
@@ -31,4 +40,5 @@ def ensure_local_distutils():
     assert '_distutils' in core.__file__, core.__file__
 
 
-ensure_local_distutils()
+if enabled():
+    ensure_local_distutils()