Backfilled messages are replayed after messages triggering the backfill

[progval]

When the homeserver the bridge runs on didn't get messages A and B from user 1 for whatever reason, and user 2 sends message C that gets through (eg. because user 2 is not on the same HS as 1), the bridge sends C first, then B and A thanks to backfilling from 2's homeserver.

I have only observed this when the backfill included a join of user 1 puppet, so it's possible that it's another instance of #1572 and the order would be C, then A then B if #1572 got fixed.

[progval]

I have only observed this when the backfill included a join of user 1 puppet, so it's possible that it's another instance of #1572 and the order would be C, then A then B if #1572 got fixed.

yeah, turns out it is