Added full URL to debug output if something doesn't look like an http hg repo.

This way it is easier to debug problems with failing subcommands, like
changegroupsubset due to permission problems, when generally accessing
the repository works fine.

mercurial/httprepo.py

@@ -288,6 +288,7 b' class httprepository(remoterepository):'
         if not (proto.startswith('application/mercurial-') or
                 proto.startswith('text/plain') or
                 proto.startswith('application/hg-changegroup')):
+            self.ui.debug(_("Requested URL: '%s'\n") % cu)
             raise hg.RepoError(_("'%s' does not appear to be an hg repository")
                                % self._url)