mercurial/changelog.py

--- a/mercurial/changelog.py	Mon Jan 07 02:00:43 2013 +0100
+++ b/mercurial/changelog.py	Wed Jan 02 01:40:06 2013 +0100
@@ -124,7 +124,7 @@
         self._realopener = opener
         self._delayed = False
         self._divert = False
-        self.filteredrevs = ()
+        self.filteredrevs = frozenset()
 
     def tip(self):
         """filtered version of revlog.tip"""