diff -r 45b86dbabbda -r ae5f7be2b4ab mercurial/commands.py
--- a/mercurial/commands.py	Mon Oct 05 03:50:47 2015 -0700
+++ b/mercurial/commands.py	Tue Sep 29 00:18:49 2015 -0700
@@ -6595,10 +6595,8 @@
 
         if check:
             cmdutil.bailifchanged(repo, merge=False)
-            if rev is None:
-                rev = repo[repo[None].branch()].rev()
-        elif rev is None:
-            rev = destutil.destupdate(repo, clean=clean)
+        if rev is None:
+            rev = destutil.destupdate(repo, clean=clean, check=check)
 
         repo.ui.setconfig('ui', 'forcemerge', tool, 'update')