imap: Don't cancel sync if client disconnects in the middle. Fixes "Message count decreased" errors.
imap: Don't cancel sync if client disconnects in the middle.
Fixes "Message count decreased" errors.

LTD-Beget/dovecot,LTD-Beget/dovecot,LTD-Beget/dovecot,LTD-Beget/dovecot,LTD-Beget/dovecot