Monkey-patch the write_pkg_info method on Python 3.1 DistributionMetadata. Fixes #197

CHANGES.txt

@@ -2,6 +2,13 @@
 CHANGES
 =======
 
+---
+3.5
+---
+
+* Issue #197: On Python 3.1, PKG-INFO is now saved in a UTF-8 encoding instead
+  of ``sys.getpreferredencoding`` to match the behavior on Python 2.6-3.4.
+
 -----
 3.4.4
 -----

setuptools/dist.py

@@ -7,6 +7,7 @@ import warnings
 import distutils.log
 import distutils.core
 import distutils.cmd
+import distutils.dist
 from distutils.core import Distribution as _Distribution
 from distutils.errors import (DistutilsOptionError, DistutilsPlatformError,
     DistutilsSetupError)
@@ -31,6 +32,26 @@ def _get_unpatched(cls):
 
 _Distribution = _get_unpatched(_Distribution)
 
+def _patch_distribution_metadata_write_pkg_info():
+    """
+    Workaround issue #197 - Python 3.1 uses an environment-local encoding to
+    save the pkg_info. Monkey-patch its write_pkg_info method to correct
+    this undesirable behavior.
+    """
+    if sys.version_info[:2] != (3,1):
+        return
+
+    # from Python 3.4
+    def write_pkg_info(self, base_dir):
+        """Write the PKG-INFO file into the release tree.
+        """
+        with open(os.path.join(base_dir, 'PKG-INFO'), 'w',
+                  encoding='UTF-8') as pkg_info:
+            self.write_pkg_file(pkg_info)
+
+    distutils.dist.DistributionMetadata.write_pkg_info = write_pkg_info
+_patch_distribution_metadata_write_pkg_info()
+
 sequence = tuple, list
 
 def check_importable(dist, attr, value):