diff -r 58bd6a58365d Lib/packaging/tests/test_util.py
--- a/Lib/packaging/tests/test_util.py	Wed Feb 08 04:09:37 2012 +0100
+++ b/Lib/packaging/tests/test_util.py	Thu Feb 09 01:42:24 2012 +0200
@@ -243,8 +243,11 @@
         self.assertRaises(PackagingPlatformError,
                           change_root, 'c:\\root', 'its\\here')
 
-        # XXX platforms to be covered: os2, mac
-
+        # os2
+        os.name = 'os2'
+        self.assertEqual(change_root('new', '/ole'),
+                         'new\\ole')
+        
     def test_split_quoted(self):
         self.assertEqual(split_quoted('""one"" "two" \'three\' \\four'),
                          ['one', 'two', 'three', 'four'])