diff -c -L /usr/local/share/emacs/23.1.50/lisp/simple.el.gz -L /tmp/buffer-content-5442SIK /tmp/jka-com5442fSQ /tmp/buffer-content-5442SIK
*** /usr/local/share/emacs/23.1.50/lisp/simple.el.gz
--- /tmp/buffer-content-5442SIK
***************
*** 3034,3043 ****
  
  (defun yank-pop (&optional arg)
    "Replace just-yanked stretch of killed text with a different stretch.
! This command is allowed only immediately after a `yank' or a `yank-pop'.
! At such a time, the region contains a stretch of reinserted
! previously-killed text.  `yank-pop' deletes that text and inserts in its
! place a different stretch of killed text.
  
  With no argument, the previous kill is inserted.
  With argument N, insert the Nth previous kill.
--- 3034,3040 ----
  
  (defun yank-pop (&optional arg)
    "Replace just-yanked stretch of killed text with a different stretch.
! If there is no such killed text, simply yank.
  
  With no argument, the previous kill is inserted.
  With argument N, insert the Nth previous kill.
***************
*** 3050,3077 ****
  `yank-excluded-properties' and `yank-handler' as described in the
  doc string for `insert-for-yank-1', which see."
    (interactive "*p")
-   (if (not (eq last-command 'yank))
-       (error "Previous command was not a yank"))
    (setq this-command 'yank)
!   (unless arg (setq arg 1))
!   (let ((inhibit-read-only t)
! 	(before (< (point) (mark t))))
!     (if before
! 	(funcall (or yank-undo-function 'delete-region) (point) (mark t))
!       (funcall (or yank-undo-function 'delete-region) (mark t) (point)))
!     (setq yank-undo-function nil)
!     (set-marker (mark-marker) (point) (current-buffer))
!     (insert-for-yank (current-kill arg))
!     ;; Set the window start back where it was in the yank command,
!     ;; if possible.
!     (set-window-start (selected-window) yank-window-start t)
!     (if before
! 	;; This is like exchange-point-and-mark, but doesn't activate the mark.
! 	;; It is cleaner to avoid activation, even though the command
! 	;; loop would deactivate the mark because we inserted text.
! 	(goto-char (prog1 (mark t)
! 		     (set-marker (mark-marker) (point) (current-buffer))))))
!   nil)
  
  (defun yank (&optional arg)
    "Reinsert (\"paste\") the last stretch of killed text.
--- 3047,3074 ----
  `yank-excluded-properties' and `yank-handler' as described in the
  doc string for `insert-for-yank-1', which see."
    (interactive "*p")
    (setq this-command 'yank)
!   (if (not (eq last-command 'yank))
!       (yank arg)
!     (unless arg (setq arg 1))
!     (let ((inhibit-read-only t)
! 	  (before (< (point) (mark t))))
!       (if before
! 	  (funcall (or yank-undo-function 'delete-region) (point) (mark t))
! 	(funcall (or yank-undo-function 'delete-region) (mark t) (point)))
!       (setq yank-undo-function nil)
!       (set-marker (mark-marker) (point) (current-buffer))
!       (insert-for-yank (current-kill arg))
!       ;; Set the window start back where it was in the yank command,
!       ;; if possible.
!       (set-window-start (selected-window) yank-window-start t)
!       (if before
! 	  ;; This is like exchange-point-and-mark, but doesn't activate the mark.
! 	  ;; It is cleaner to avoid activation, even though the command
! 	  ;; loop would deactivate the mark because we inserted text.
! 	  (goto-char (prog1 (mark t)
! 		       (set-marker (mark-marker) (point) (current-buffer))))))
!     nil))
  
  (defun yank (&optional arg)
    "Reinsert (\"paste\") the last stretch of killed text.

Diff finished.  Mon Jun 14 23:50:10 2010