Add comment to Distutil files about requiring 1.5.2 compatibility, as
    suggested by PEP 291.
diff --git a/Lib/distutils/dep_util.py b/Lib/distutils/dep_util.py
index f496654..0746633 100644
--- a/Lib/distutils/dep_util.py
+++ b/Lib/distutils/dep_util.py
@@ -4,6 +4,8 @@
 and groups of files; also, function based entirely on such
 timestamp dependency analysis."""
 
+# This module should be kept compatible with Python 1.5.2.
+
 __revision__ = "$Id$"
 
 import os