* We only need to fetch users in private rooms
* Filter out `user_id` at the top
* Discard excluded users in the top loop
We weren't doing this in the "First, if they're our user" branch so this
is a bugfix.
* The caller must check that `user_id` is included
This is in the docstring. There are two call sites:
- one in `_handle_room_publicity_change`, which explicitly checks before calling;
- and another in `_handle_room_membership_event`, which returns early if
the user is excluded.
So this change is safe.
* Test joining a private room with an excluded user
* Tweak an existing test
* Changelog
* test docstring
* lint
