(ITS#8931) deref'ing non-existent attributes should not result in protocolError

Full_Name: Version: RE24 OS: URL: Submission from: (NULL) (46.183.103.8)

In aehostd I try to limit the number of required search requests. Therefore I'm using the deref control to read group and sudoers entries referenced in service groups.

If there are no such references (yet) slapd currently returns protocolError. IMO this is wrong.

It should simply omit the deref response control and the client has to deal with that.

(No, to save round-trips, log-space and data traffic I don't want to read the service groups first to determine whether which deref attributes are present.)