unhandled case: login via backup/bot-token and then `key lock`

[maxtaco]

• the issue is that we wind up with an entry in the users map, but not conceivable path to resurrect the key, since it's been cleared
• probably the easiest thing to do is to remove the entry from the users map, thus effectively resetting the agent
• should test this with a simple test, since it feels like something that can break again if we are not careful