mbox: Don't close input stream when syncing. This breaks copying.
mbox: Don't close input stream when syncing. This breaks copying.

--HG--
branch : HEAD

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