* Add tests
* Ensure deleted statuses are marked as such
* Save some redis memory by not storing URIs in delete_upon_arrival values
* Avoid possible race condition when processing incoming Deletes
* Avoid potential duplicate Delete forwards
* Lower lock durations to reduce issues in case of hard crash of the Rails process
* Check for `lock.aquired?` and improve comment
* Refactor RedisLock usage in app/lib/activitypub
* Fix using incorrect or non-existent sender for relaying Deletes