Handle tombstoned rooms properly to avoid adding the same room multiple times

[kevinaboos]

Here's an example, in which the room "The Office of the Matrix Foundation" has been tombstoned and replaced with a new room, but they have the same room_id: "!CltYqaqkvHpbwjPFcs:matrix.org".

This causes the timeline_update_receiver created in add_new_room() to be replaced in ALL_ROOMS_INFO, which in turn causes the old one to be dropped. Then, when the original room instance attempts to send an update, the timeline_update_sender.send() call fails because the corresponding receiver has been dropped.

Below is the log output:

src/sliding_sync.rs:930:5 - Populating initial set of 0 known rooms.
src/home/rooms_list.rs:243:17 - RoomsList: processed 1 updates to the list of all rooms
2024-10-08T18:31:18.643267Z  INFO matrix_sdk::encryption::recovery: Recovery state changed from Unknown to Incomplete
2024-10-08T18:31:18.713080Z  WARN matrix_sdk_crypto::identities::manager: Our own device might have been deleted user_id="@kevinaboos:matrix.org" device_id="BVMLCDKGQG" curve25519_key="curve25519:r6vBTV0GY/lJFX0ue6baJBJC44V04+y2hP8OBlRwdV4" ed25519_key="ed25519:/KgR6H0N857EXycYD6WotNCkM6gUVjaf0qVGLkb/2CM"
src/sliding_sync.rs:963:46 - room_list: diff PushBack
src/sliding_sync.rs:1050:5 - Adding new room: "Empty Room", room_id: !CltYqaqkvHpbwjPFcs:matrix.org
2024-10-08T18:31:19.515965Z  INFO matrix_sdk_ui::room_list_service::room: No cached sliding sync room found for `!CltYqaqkvHpbwjPFcs:matrix.org`, the timeline will be empty.
src/sliding_sync.rs:1141:13 - Received an updated ignored-user list: []
src/sliding_sync.rs:1192:13 - Received a room list loading state update: Loaded { maximum_number_of_rooms: Some(29) }
src/home/rooms_list.rs:243:17 - RoomsList: processed 1 updates to the list of all rooms
2024-10-08T18:31:19.926715Z  WARN build{room_id="!CltYqaqkvHpbwjPFcs:matrix.org" track_read_receipts=true}: matrix_sdk_base::rooms::normal: Unknown room version, falling back to v10
2024-10-08T18:31:19.931166Z  INFO sending_task{room_id=!CltYqaqkvHpbwjPFcs:matrix.org}: matrix_sdk::send_queue: spawned the sending task
2024-10-08T18:31:19.931828Z  INFO local_echo_handler{room_id="!CltYqaqkvHpbwjPFcs:matrix.org"}: matrix_sdk_ui::timeline::builder: spawned the local echo handler!
src/sliding_sync.rs:1214:5 - Starting timeline subscriber for room !CltYqaqkvHpbwjPFcs:matrix.org...
src/sliding_sync.rs:1009:46 - room_list: diff Reset, new length 20
src/sliding_sync.rs:1050:5 - Adding new room: "Office of the Matrix.org Foundation", room_id: !CltYqaqkvHpbwjPFcs:matrix.org
src/sliding_sync.rs:1216:5 - Received initial timeline update of 2 items for room !CltYqaqkvHpbwjPFcs:matrix.org.
thread 'tokio-runtime-worker' panicked at src/sliding_sync.rs:1223:14:
Error: timeline update sender couldn't send update to room !CltYqaqkvHpbwjPFcs:matrix.org with initial items!

The key lines are:

src/sliding_sync.rs:1050:5 - Adding new room: "Empty Room", room_id: !CltYqaqkvHpbwjPFcs:matrix.org

and

src/sliding_sync.rs:1050:5 - Adding new room: "Office of the Matrix.org Foundation", room_id: !CltYqaqkvHpbwjPFcs:matrix.org

[kevinaboos]

This is currently blocked on Matrix SDK's issue, in which we cannot get a room's tombstoned state events.
matrix-org/matrix-rust-sdk#4211