dsync: Don't repeatedly try to keep opening the same failing mailbox.
dsync: Don't repeatedly try to keep opening the same failing mailbox.

--HG--
branch : HEAD

jwm/dovecot-notmuch,jwm/dovecot-notmuch,jwm/dovecot-notmuch,jwm/dovecot-notmuch,jkerihuel/dovecot,jkerihuel/dovecot,jkerihuel/dovecot,jkerihuel/dovecot,jwm/dovecot-notmuch,jkerihuel/dovecot