diff -r 705ecab649ea -r aea06029919e mercurial/graphmod.py
--- a/mercurial/graphmod.py	Sat Feb 18 18:00:01 2017 +0900
+++ b/mercurial/graphmod.py	Sun Feb 19 18:16:09 2017 +0900
@@ -22,6 +22,7 @@
 from .node import nullrev
 from . import (
     revset,
+    smartset,
     util,
 )
 
@@ -67,8 +68,8 @@
             if gp is None:
                 # precompute slow query as we know reachableroots() goes
                 # through all revs (issue4782)
-                if not isinstance(revs, revset.baseset):
-                    revs = revset.baseset(revs)
+                if not isinstance(revs, smartset.baseset):
+                    revs = smartset.baseset(revs)
                 gp = gpcache[mpar] = sorted(set(revset.reachableroots(
                     repo, revs, [mpar])))
             if not gp: