More sane handling of group errors and pep8

synapse/handlers/groups_local.py

@@ -20,7 +20,7 @@ from six import iteritems
 
 from twisted.internet import defer
 
-from synapse.api.errors import (SynapseError, HttpResponseException)
+from synapse.api.errors import (HttpResponseException, SynapseError)
 from synapse.types import get_domain_from_id
 
 logger = logging.getLogger(__name__)
@@ -40,12 +40,13 @@ def _create_rerouter(func_name):
             d = getattr(self.transport_client, func_name)(
                 destination, group_id, *args, **kwargs
             )
+
             def h(failure):
                 failure.trap(HttpResponseException)
                 e = failure.value
-                if e.code >= 400 and e.code < 500:
-                    raise SynapseError(e.code, e.msg)
-                failure.raiseException()
+                if e.code == 403:
+                    raise e.to_synapse_error()
+                return failure
             d.addErrback(h)
             return d
     return f