Ensure that mumble and mumble-server will be in Buster
Originally created by @segfault on #15603 (Redmine)
The mumble and mumble-server packages were removed from Debian Testing last week. The reason seems to be this unsolved bug.
Mumble is one of the core features of Tails Server, so I think it would be really bad if we wouldn’t have it in Buster. I hope this will be fixed by the Debian maintainer or Mumble, but in the worst case I will try to fix this in time for the Buster freeze (which doesn’t have a date yet).