mdbox: Don't leave extra records to dovecot.map.index if mailbox index locking fails. Fixes errors such as: Corrupted dbox file /mdbox/storage/m.1 (around offset=2652): EOF reading msg header (got 0/30 bytes)
mdbox: Don't leave extra records to dovecot.map.index if mailbox index locking fails.
Fixes errors such as:
Corrupted dbox file /mdbox/storage/m.1 (around offset=2652): EOF reading msg header (got 0/30 bytes)

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