diff -r 447332970d7b -r 3185b347ae98 mercurial/worker.py
--- a/mercurial/worker.py	Tue Jul 16 11:18:16 2013 -0500
+++ b/mercurial/worker.py	Tue Jul 16 11:53:53 2013 -0500
@@ -109,7 +109,7 @@
     def waitforworkers():
         for _ in pids:
             st = _exitstatus(os.wait()[1])
-            if st and not problem:
+            if st and not problem[0]:
                 problem[0] = st
                 killworkers()
     t = threading.Thread(target=waitforworkers)