bug / acl support in accessing index?

also bug/no acl support in accessing index

dovecot[28746]: imap(usertest6)<29630><lnLuusciSa0ucGwC>: Error: fchown(..../shared/usertest/index/mailboxes.lockcfcdcd07648b68e0, group=10001(usertest)) failed: Operation not permitted (egid=10006, group based on ..../shared/usertest/mdbox - see http://wiki2.dovecot.org/Errors/ChgrpNoPerm)

su usertest6 can just touch files in the index folder