httppeer: unify hint message for PeerTransportError

Another raising PeerTransportError for "incomplete response" in
httppeer.py uses this (changed) hint message. This unification reduces
cost of translation.

mercurial/httppeer.py

@@ -80,7 +80,7 b' def _wraphttpresponse(resp):'
             except httplib.HTTPException as e:
                 raise error.PeerTransportError(
                     _('HTTP request error (%s)') % e,
-                    hint=_('this may be an intermittent failure; '
+                    hint=_('this may be an intermittent network failure; '
                            'if the error persists, consider contacting the '
                            'network or server operator'))