(maybe) fix handlers.test_federation_event.FederationEventHandlerTests.test_process_pulled_event_with_rejected_missing_state() by introducing a member that can match power levels with the remote member sending rejected power level events

I believe this is caused by the room creator being the member to send
the final power levels event. It failed the reverse topological sort in
inverted order(the two events were swapped places). Since the room
creator has an infinitely higher power level than the remote user, the
reverse topological sort should have fallen to the origin_server_ts as
the last fallback and it was not

Author: jason-famedly

tests/handlers/test_federation_event.py

@@ -830,6 +830,9 @@ def test_process_pulled_event_with_rejected_missing_state(self) -> None:
         )
         room_version = self.get_success(main_store.get_room_version(room_id))
 
+        ernie_user_id = self.register_user("ernie", "test")
+        ernie_tok = self.login("ernie", "test")
+        self.helper.join(room_id, user=ernie_user_id, tok=ernie_tok)
         # Add another local user to the room. This user is going to be kicked in a
         # rejected event.
         bert_user_id = self.register_user("bert", "test")
@@ -838,13 +841,13 @@ def test_process_pulled_event_with_rejected_missing_state(self) -> None:
 
         # Allow the remote user to kick bert.
         # The remote user is going to send a rejected power levels event later on and we
-        # need state resolution to order it before another power levels event kermit is
+        # need state resolution to order it before another power levels event ernie is
         # going to send later on. Hence we give both users the same power level, so that
         # ties are broken by `origin_server_ts`.
         self.helper.send_state(
             room_id,
             "m.room.power_levels",
-            {"users": {kermit_user_id: 100, OTHER_USER: 100}},
+            {"users": {ernie_user_id: 100, OTHER_USER: 100}},
             tok=kermit_tok,
         )
 
@@ -1008,8 +1011,8 @@ def test_process_pulled_event_with_rejected_missing_state(self) -> None:
                 self.helper.send_state(
                     room_id,
                     "m.room.power_levels",
-                    {"users": {kermit_user_id: 100, OTHER_USER: 100, bert_user_id: 1}},
-                    tok=kermit_tok,
+                    {"users": {ernie_user_id: 100, OTHER_USER: 100, bert_user_id: 1}},
+                    tok=ernie_tok,
                 )["event_id"]
             )
         )