diff -r 7f5dab94e48c -r 1e6b5faf9d4e mercurial/commands.py
--- a/mercurial/commands.py	Wed Nov 07 16:21:39 2012 -0600
+++ b/mercurial/commands.py	Mon Nov 12 19:27:03 2012 +0200
@@ -2936,7 +2936,7 @@
     def matchlines(body):
         begin = 0
         linenum = 0
-        while True:
+        while True and begin < len(body):
             match = regexp.search(body, begin)
             if not match:
                 break