diff -r 697289c5d415 -r cd6f10dccf16 mercurial/cmdutil.py
--- a/mercurial/cmdutil.py	Tue Oct 11 21:10:03 2011 -0400
+++ b/mercurial/cmdutil.py	Tue Oct 11 18:18:15 2011 -0700
@@ -75,6 +75,10 @@
     modified, added, removed, deleted = repo.status()[:4]
     if modified or added or removed or deleted:
         raise util.Abort(_("outstanding uncommitted changes"))
+    ctx = repo[None]
+    for s in ctx.substate:
+        if ctx.sub(s).dirty():
+            raise util.Abort(_("uncommitted changes in subrepo %s") % s)
 
 def logmessage(ui, opts):
     """ get the log message according to -m and -l option """