anchor.diff:  (defvar *buffer-list* nil)
   
   (defun add-buffer (buffer)
  +  (check-type buffer buffer)
     (unless (ghost-buffer-p buffer)
       (assert (not (get-buffer (buffer-name buffer))))
       (push buffer *buffer-list*)))
  
positive.code:         (car buffer-list))))
  
  (defun update-prev-buffer (buffer)
    (setq *buffer-list*
          (cons buffer
                (delete buffer (buffer-list)))))
  
  (defun set-buffer (buffer &optional (update-prev-buffer-p t))
    (check-switch-minibuffer-window)
    (unless (eq (current-buffer) buffer)
      (when update-prev-buffer-p
  
negative.code:         (car buffer-list))))
  
  (defun bury-buffer (buffer)
    (check-type buffer buffer)
    (setf *buffer-list*
          (append (delete buffer (buffer-list))
                  (list buffer)))
  