Clarify list/set/dict/tuple comprehensions and enforce via flake8 (#6957)

Ensure good comprehension hygiene using flake8-comprehensions.

1 files changed, 2 insertions, 2 deletions

diff --git a/synapse/federation/send_queue.py b/synapse/federation/send_queue.py

index 001bb304ae..876fb0e245 100644
--- a/synapse/federation/send_queue.py
+++ b/synapse/federation/send_queue.py
@@ -129,9 +129,9 @@ class FederationRemoteSendQueue(object):
             for key in keys[:i]:
                 del self.presence_changed[key]
 
-            user_ids = set(
+            user_ids = {
                 user_id for uids in self.presence_changed.values() for user_id in uids
-            )
+            }
 
             keys = self.presence_destinations.keys()
             i = self.presence_destinations.bisect_left(position_to_delete)