Deleting a lobby deletes all lobbies

Steps to reproduce:
- Create a first new lobby
- Wait a bit
- Create a second new lobby
- Check the list at '/admin/lobbies' and see 2 lobbies
- Wait for first lobby to expire (this is easier if you reduce LOBBY_LIFESPAN)

Expect:
- /admin/lobbies Now shows just the second lobby

Actual:
- /admin/lobbies Now shows no lobbies
