diff -r bcdfb6078b9f -r 12dbdd348bb0 mercurial/commands.py
--- a/mercurial/commands.py	Fri May 10 00:26:39 2013 +0400
+++ b/mercurial/commands.py	Tue May 07 23:49:03 2013 +0900
@@ -943,6 +943,9 @@
 
     Returns 0 on success.
     """
+    if label:
+        label = label.strip()
+
     if not opts.get('clean') and not label:
         ui.write("%s\n" % repo.dirstate.branch())
         return