mail_index_update_headers() seeked always to beginning of file, instead of beginning of message, which broke mbox.
mail_index_update_headers() seeked always to beginning of file, instead of
beginning of message, which broke mbox.

--HG--
branch : HEAD

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