--- a/mercurial/revset.py	Mon Sep 12 13:37:14 2016 +0200
+++ b/mercurial/revset.py	Sat Oct 01 20:11:48 2016 +0900
@@ -366,8 +366,9 @@
 
     if not m or not n:
         return baseset()
-    m, n = m.first(), n.last()
-
+    return _makerangeset(repo, subset, m.first(), n.last(), order)
+
+def _makerangeset(repo, subset, m, n, order):
     if m == n:
         r = baseset([m])
     elif n == node.wdirrev: