--- a/mercurial/revlog.py Wed Jul 11 16:21:41 2018 -0700
+++ b/mercurial/revlog.py Wed Jul 11 16:37:30 2018 -0700
@@ -1656,6 +1656,8 @@
return True
elif a == b:
return True
+ elif a < b:
+ return False
return b in self._commonancestorsheads(a, b)
def commonancestorsheads(self, a, b):