Lower fetch bound further

changelog.d/17914.bugfix

@@ -0,0 +1 @@
+Limit event fetches in test to prevent stack size from growing too large.

tests/storage/databases/main/test_events_worker.py

@@ -452,7 +452,9 @@ class DatabaseOutageTestCase(unittest.HomeserverTestCase):
         with self._outage():
             # Kick off a bunch of event fetches but do not pump the reactor
             event_deferreds = []
-            for event_id in self.event_ids:
+            # Limit the number of event_ids otherwise the total stack size grows too
+            # large for our custom twisted patch.
+            for event_id in self.event_ids[0:10]:
                 event_deferreds.append(ensureDeferred(self.store.get_event(event_id)))
 
             # We should have maxed out on event fetcher threads