diff -r 3e61b325e79a -r e4f27fb65da7 mercurial/merge.py
--- a/mercurial/merge.py	Thu Oct 01 20:31:43 2015 -0700
+++ b/mercurial/merge.py	Mon Oct 05 01:47:33 2015 -0700
@@ -997,8 +997,6 @@
             nodes = list(repo.set('_updatedefaultdest()'))
             if nodes:
                 node = nodes[0].node()
-                if p1.obsolete() and not p1.children():
-                    pas = [p1]
 
         overwrite = force and not branchmerge