diff -r 60bbd4f9abd1 -r 014044dbd4e8 mercurial/graphmod.py
--- a/mercurial/graphmod.py	Mon Aug 24 15:40:42 2015 -0700
+++ b/mercurial/graphmod.py	Fri Aug 21 16:03:25 2015 -0700
@@ -247,7 +247,8 @@
         if firstbranchrevset:
             firstbranch = repo.revs(firstbranchrevset)
         parentrevs = repo.changelog.parentrevs
-        revs = list(groupbranchiter(revs, parentrevs, firstbranch))
+        revs = groupbranchiter(revs, parentrevs, firstbranch)
+        revs = revset.baseset(revs)
 
     for rev in revs:
         ctx = repo[rev]