Fix ambiguous column name that would prevent use of MSC2716 History Import when using Postgres as a database. (#12843)

Author: reivilibre

changelog.d/12843.bugfix

@@ -0,0 +1 @@
+Fix bug where servers using a Postgres database would fail to backfill from an insertion event when MSC2716 is enabled (`experimental_features.msc2716_enabled`).

synapse/storage/databases/main/event_federation.py

@@ -1057,7 +1057,7 @@ def _get_connected_batch_event_backfill_results_txn(
             INNER JOIN batch_events AS c
             ON i.next_batch_id = c.batch_id
             /* Get the depth of the batch start event from the events table */
-            INNER JOIN events AS e USING (event_id)
+            INNER JOIN events AS e ON c.event_id = e.event_id
             /* Find an insertion event which matches the given event_id */
             WHERE i.event_id = ?
             LIMIT ?