Avoid “error: None” messages from distutils (#4931).

Thanks to Amaury Forgeot d’Arc and Philip J. Eby.
diff --git a/Misc/NEWS b/Misc/NEWS
index e974ee4..2fce437 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -44,6 +44,9 @@
   as documented.  The pattern and source keyword parameters are left as
   deprecated aliases.
 
+- Issue #4931: distutils should not produce unhelpful "error: None" messages
+  anymore.  distutils.util.grok_environment_error is kept but doc-deprecated.
+
 - Improve the random module's default seeding to use 256 bits of entropy
   from os.urandom().  This was already done for Python 3, mildly improving
   security with a bigger seed space.