Fix check of wrong variable

synapse/replication/resource.py

@@ -238,7 +238,7 @@ def events(self, writer, current_token, limit, request_streams):
         request_backfill = request_streams.get("backfill")
 
         if request_events is not None or request_backfill is not None:
-            if request_backfill is None:
+            if request_events is None:
                 request_events = current_token.events
             if request_backfill is None:
                 request_backfill = current_token.backfill