jmuc presence -a can't possibly work

[nelhage@mit.edu]

The outer jmuc command uses -a to detect an account name, and bails if can't find one. So, if you're logged into multiple accounts, jmuc presence -a causes it to find an empty JID, and then see that there are multiple accounts, so there is no default JID, and then die complaining that you need to use -a to specify an account.

[andersk@mit.edu]

It’s not _completely_ broken: it works if the current message is a Jabber message (so it can get the default account from that message), or if you do jmuc presence -a mit.edu -a.