Prevent message search in upgraded rooms we're not in

[anoadragon453]

Fixes #6356

I assume this is preferred instead of attempting to join the predecessor room before searching it, as that could be slow and we may not be able to join.

old

old

[richvdh]

I don't think this fixes the bug...

old

[richvdh]

sorry anoa, but this feels like a very complicated way of solving the problem. How about this:

        # the initial room must have been known for us to get this far.
        predecessor_room = yield self.store.get_room_predecessor(room_id)

        while True:
            if not predecessor_room:
                # We have reached the end of the chain of predecessors
                break

            predecessor_room_id = predecessor["room_id"]

            # don't add it to the list until we have checked that we are in the room.
            try:
                next_predecessor_room = yield self.store.get_room_predecessor(
                    predecessor_room_id
                )
            except NotFoundError:
                # The predecessor is not a known room, so we are done here
                break
            
            historical_room_ids.append(predecessor_room_id)

             # and repeat
            predecessor_room = next_predecessor_room

        return historical_room_ids

[anoadragon453]

predecessor_room_id = predecessor["room_id"]

We would still need to check that predecessor actually contained a room_id first, right?

[anoadragon453]

I've implemented a very similar version, thanks :)

old

[richvdh]

lgmt!

[richvdh]

lgtm