bug#22804: 25.1.50; undo bug

[Richard Stallman]

Type this text into an empty buffer in Fundamental mode:

   This is a test.<ret>

Go to the end of 'this' and type C-t.  It produces "Thi sis..."
Type C-n.
Type C-_.

It leaves point at the end, rather than where it undid the change.




In GNU Emacs 25.1.50.1 (i686-pc-linux-gnu, GTK+ Version 2.24.23)
 of 2015-12-25
Repository revision: 608b15d59d08ff7054fdc5458d1d2ae54dd043e2
System Description:     Trisquel GNU/Linux 7.0, Belenos

Configured using:
 'configure 'CFLAGS=-g -O0''

Configured features:
XPM JPEG TIFF GIF PNG RSVG SOUND GPM DBUS GCONF GSETTINGS NOTIFY
LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS GTK2 X11

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Fundamental

Minor modes in effect:
  diff-auto-refine-mode: t
  shell-dirtrack-mode: t
  gpm-mouse-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t
  abbrev-mode: t

Recent messages:
Saving file /home/rms/articles/depends-on-nonfree...
Wrote /home/rms/articles/depends-on-nonfree
Auto-saving...done
Saving file /home/rms/articles/depends-on-nonfree...
Wrote /home/rms/articles/depends-on-nonfree
Undo! [2 times]
Saving file /home/rms/articles/depends-on-nonfree...
Wrote /home/rms/articles/depends-on-nonfree
(New file)
Undo!

Load-path shadows:
None found.

Features:
(apropos goto-addr vc vc-dispatcher vc-git map bookmark doc-view
image-mode rect utf-7 rmailedit tabify imenu man sh-script smie
executable conf-mode mailcap pcmpl-gnu pcmpl-unix unrmail mail-extr
shadow emacsbug eieio-opt speedbar sb-image ezimage dframe find-func
compare-w thingatpt xref project parse-time vc-cvs sgml-mode cc-mode
cc-fonts cc-guess cc-menus cc-cmds cc-styles cc-align cc-engine
cc-vars cc-defs diff-mode easy-mmode diff pp wid-edit descr-text
texinfo jka-compr battery dired-aux novice two-column kmacro
iso-transl cal-move cal-menu calendar cal-loaddefs epa-mail quail
dabbrev character-fold misearch multi-isearch shell pcomplete grep
compile comint ansi-color ring ispell rmailout rmailkwd epa derived
epg rmailsum qp mailalias url-util shr dom subr-x browse-url rmailmm
message sendmail format-spec rfc822 mml mml-sec mm-decode mm-bodies
mm-encode mailabbrev gmm-utils mailheader mail-parse rfc2231 rmail
rmail-loaddefs rfc2047 rfc2045 ietf-drums mail-utils dired
dired-loaddefs seq t-mouse view paren cus-start cus-load advice
finder-inf package epg-config url-handlers url-parse auth-source
cl-seq eieio byte-opt bytecomp byte-compile cl-extra cconv eieio-core
cl-macs gv eieio-loaddefs gnus-util time-date mm-util help-fns
help-mode easymenu cl-loaddefs pcase cl-lib mail-prsvr password-cache
url-vars mule-util tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel x-win term/common-win x-dnd tool-bar dnd
fontset image regexp-opt fringe tabulated-list newcomment elisp-mode
lisp-mode prog-mode register page menu-bar rfn-eshadow timer select
scroll-bar mouse jit-lock font-lock syntax facemenu font-core frame
cl-generic cham georgian utf-8-lang misc-lang vietnamese tibetan thai
tai-viet lao korean japanese eucjp-ms cp51932 hebrew greek romanian
slovak czech european ethiopic indian cyrillic chinese charscript
case-table epa-hook jka-cmpr-hook help simple abbrev obarray
minibuffer cl-preloaded nadvice loaddefs button faces cus-face
macroexp files text-properties overlay sha1 md5 base64 format env
code-pages mule custom widget hashtable-print-readable backquote
dbusbind inotify dynamic-setting system-font-setting
font-render-setting move-toolbar gtk x-toolkit x multi-tty
make-network-process emacs)

Memory information:
((conses 8 955446 152688)
 (symbols 24 42634 51)
 (miscs 20 23970 6642)
 (strings 16 83914 46370)
 (string-bytes 1 3083607)
 (vectors 8 42845)
 (vector-slots 4 1708915 59104)
 (floats 8 358 686)
 (intervals 28 160417 2261)
 (buffers 520 588)
 (heap 1024 54274 3603))
[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]


-- 
Dr Richard Stallman
President, Free Software Foundation (gnu.org, fsf.org)
Internet Hall-of-Famer (internethalloffame.org)
Skype: No way! See stallman.org/skype.html.