sync: DELSUB on non-existant mailbox

[Per olof Ljungmark]

On a sync job running from cron to the tape backup server I get this on 
a few mailboxes. Problem is, the ones below are nowhere to be found on 
master or slave.

Where does sync_client fetch the mailbox info from?

DELSUB username INBOX^INBOX^Drafts
DELSUB username INBOX^INBOX^Sent
DELSUB username INBOX^INBOX^Trash
DELSUB username INBOX^Trash^INBOX^Drafts
DELSUB username INBOX^Trash^INBOX^Sent
DELSUB username INBOX^Trash^INBOX^Trash