--- a/mercurial/verify.py	Mon Nov 22 17:57:11 2010 +0100
+++ b/mercurial/verify.py	Mon Nov 22 18:15:58 2010 +0100
@@ -34,7 +34,7 @@
         raise util.Abort(_("cannot verify bundle or remote repos"))
 
     def err(linkrev, msg, filename=None):
-        if linkrev != None:
+        if linkrev is not None:
             badrevs.add(linkrev)
         else:
             linkrev = '?'