diff -r f458a6701983 -r 4f49810a1011 mercurial/destutil.py
--- a/mercurial/destutil.py	Thu Jun 29 11:29:19 2017 -0700
+++ b/mercurial/destutil.py	Tue Jun 27 01:03:01 2017 +0200
@@ -11,7 +11,7 @@
 from . import (
     bookmarks,
     error,
-    obsolete,
+    obsutil,
     scmutil,
 )
 
@@ -24,7 +24,7 @@
 
     if p1.obsolete() and not p1.children():
         # allow updating to successors
-        successors = obsolete.successorssets(repo, p1.node())
+        successors = obsutil.successorssets(repo, p1.node())
 
         # behavior of certain cases is as follows,
         #