diff --git a/mercurial/ancestor.py b/mercurial/ancestor.py
--- a/mercurial/ancestor.py
+++ b/mercurial/ancestor.py
@@ -331,7 +331,7 @@
 
         Result does not include the null revision."""
         self._parentrevs = pfunc
-        self._initrevs = revs = [r for r in revs if r >= stoprev]
+        self._initrevs = [r for r in revs if r >= stoprev]
         self._stoprev = stoprev
         self._inclusive = inclusive