Revert "We don't care about forgotten rooms"

This reverts commit ad8b316939.

synapse/storage/push_rule.py

@@ -184,6 +184,18 @@ class PushRuleStore(SQLBaseStore):
             if uid in local_users_in_room:
                 user_ids.add(uid)
 
+        forgotten = yield self.who_forgot_in_room(
+            event.room_id, on_invalidate=cache_context.invalidate,
+        )
+
+        for row in forgotten:
+            user_id = row["user_id"]
+            event_id = row["event_id"]
+
+            mem_id = current_state_ids.get((EventTypes.Member, user_id), None)
+            if event_id == mem_id:
+                user_ids.discard(user_id)
+
         rules_by_user = yield self.bulk_get_push_rules(
             user_ids, on_invalidate=cache_context.invalidate,
         )