Add comment to Distutil files about requiring 1.5.2 compatibility, as

suggested by PEP 291.

Lib/distutils/errors.py

@@ -8,6 +8,8 @@ usually raised for errors that are obviously the end-user's fault
 This module is safe to use in "from ... import *" mode; it only exports
 symbols whose names start with "Distutils" and end with "Error"."""
 
+# This module should be kept compatible with Python 1.5.2.
+
 __revision__ = "$Id$"
 
 class DistutilsError (Exception):