httprepo: send URL redirection notices to stderr (issue2828)

mercurial/httprepo.py

@@ -102,7 +102,8 b' class httprepository(wireproto.wirerepos'
         if resp_url.endswith(qs):
             resp_url = resp_url[:-len(qs)]
         if self._url.rstrip('/') != resp_url.rstrip('/'):
-            self.ui.status(_('real URL is %s\n') % resp_url)
+            if not self.ui.quiet:
+                self.ui.warn(_('real URL is %s\n') % resp_url)
         self._url = resp_url
         try:
             proto = resp.getheader('content-type')