diff -r 8ea51e9e7031 -r 3da456d0c885 mercurial/util.py
--- a/mercurial/util.py	Mon Nov 22 17:57:11 2010 +0100
+++ b/mercurial/util.py	Mon Nov 22 18:15:58 2010 +0100
@@ -1054,7 +1054,7 @@
 
     # NOTE: unixtime = localunixtime + offset
     offset, date = timezone(string), string
-    if offset != None:
+    if offset is not None:
         date = " ".join(string.split()[:-1])
 
     # add missing elements from defaults