`CertDB.request_service_cert` could re-create NSSDB files if the supplied CA certificate was not found in database. This could cause subtle bugs since the files were recreated with wrong permissions. This behavior was removed so that there are no destructive operations performed by the method. https://fedorahosted.org/freeipa/ticket/6429 Reviewed-By: Stanislav Laznicka <slaznick@redhat.com>