diff -r 5516fdf3fe24 -r 2de6ac4ac17c mercurial/subrepo.py
--- a/mercurial/subrepo.py	Fri May 04 14:36:40 2012 -0400
+++ b/mercurial/subrepo.py	Fri May 04 14:19:52 2012 +0200
@@ -44,6 +44,9 @@
     if '.hgsubstate' in ctx:
         try:
             for l in ctx['.hgsubstate'].data().splitlines():
+                l = l.lstrip()
+                if not l:
+                    continue
                 revision, path = l.split(" ", 1)
                 rev[path] = revision
         except IOError, err: