Include `prev_content` field in AS events (#11798)

* Include 'prev_content' field in AS events

Signed-off-by: Vaishnav Nair <nairvaishnav007@icloud.com>
Co-authored-by: Brendan Abolivier <babolivier@matrix.org>

changelog.d/11798.bugfix

+Include a `prev_content` field in state events sent to Application Services. Contributed by @totallynotvaishnav.
\ No newline at end of file

synapse/storage/databases/main/appservice.py

@@ -384,7 +384,7 @@ class ApplicationServiceTransactionWorkerStore(
             "get_new_events_for_appservice", get_new_events_for_appservice_txn
         )
 
-        events = await self.get_events_as_list(event_ids)
+        events = await self.get_events_as_list(event_ids, get_prev_content=True)
 
         return upper_bound, events