Currently bkr.common.krb_auth.get_encoded_request() will use the
socket.gethostname() value (if none is given) for the host part of a service principal when making a request.

Rightly or wrongly, this means that when the client uses one principal for the request and the server uses another principal (e.g. client uses an A record for the host and server uses a CNAME) we get the 'Wrong principal in request' error.