diff -r fae47ecaa952 -r 05390cfe678a mercurial/commands.py
--- a/mercurial/commands.py	Sat May 11 20:25:15 2013 -0500
+++ b/mercurial/commands.py	Mon May 13 13:02:01 2013 -0500
@@ -955,6 +955,9 @@
 
     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