If mbox file is deleted for selected folder, recreate it again so we can handle locking issues properly. For example mutt deletes the mbox when all mails are expunged.
If mbox file is deleted for selected folder, recreate it again so we can
handle locking issues properly. For example mutt deletes the mbox when all
mails are expunged.

--HG--
branch : HEAD

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