anchor.diff:        (process-one-reply 4-reply :a)
       (multiple-value-bind (6-addresses 6-truename 6-aliases)
           (process-one-reply 6-reply :aaaa)
  +      (declare (ignore 6-truename))
         (values (nconc 4-addresses 6-addresses)
                 4-truename
                 (nconc 4-aliases 6-aliases)))))
  
positive.code:   (multiple-value-bind (addresses truename aliases)
        (search-host-by-address address)
      (cond (addresses (values addresses truename aliases))
            (t (dns-lookup-host-by-address address ipv6)))))
  
  (defun process-one-reply (reply query-type)
    (let ((truename (dns-record-name (aref (dns-message-question reply) 0)))
  
negative.code:   (let ((condition (reply-error-condition reply query-type)))
      (and condition (error condition :data host))))
  
  (defun dns-lookup-host-by-address (address)
    (let ((reply (dns-query address :type :ptr)))
      (check-reply-for-errors reply address :ptr)
      (let ((hostname (remove-trailing-dot
  