diff --git a/mercurial/changelog.py b/mercurial/changelog.py
--- a/mercurial/changelog.py
+++ b/mercurial/changelog.py
@@ -107,6 +107,8 @@ class changelog(revlog.revlog):
         self._realopener = opener
         self._delayed = False
         self._divert = False
+        # hiddenrevs: revs that should be hidden by command and tools
+        self.hiddenrevs = set()
 
     def delayupdate(self):
         "delay visibility of index updates to other readers"