mail_index_move_to_memory(): Don't break if the index is already in memory. Fixes mbox_min_index_size.
mail_index_move_to_memory(): Don't break if the index is already in memory.
Fixes mbox_min_index_size.

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