--- a/mercurial/url.py	Sun Jul 31 01:46:52 2011 +0200
+++ b/mercurial/url.py	Mon Aug 01 23:58:50 2011 +0200
@@ -25,7 +25,7 @@
             self._writedebug(user, passwd)
             return (user, passwd)
 
-        if not user:
+        if not user or not passwd:
             res = httpconnectionmod.readauthforuri(self.ui, authuri)
             if res:
                 group, auth = res