Since empty lookups now return 200/empty list not 404, we can safely log failures as exceptions

synapse/appservice/api.py

@@ -78,9 +78,8 @@ class ApplicationServiceApi(SimpleHttpClient):
         try:
             response = yield self.get_json(uri, fields)
             defer.returnValue(response)
-        except Exception:
-            # TODO: would be noisy to log lookup failures, but we want to log
-            # other things. Hrm.
+        except Exception as ex:
+            logger.warning("query_3pu to %s threw exception %s", uri, ex)
             defer.returnValue([])
 
     @defer.inlineCallbacks