bug#46552: 27.1; image-mode should not move current point

[ynyaaa]

If an image which is a binary file is opened in image-mode,
the current point is moved from the beginning of the buffer to
elsewhere. And if the image display is toggled off and on again,
the current point is moved to the end of the buffer.
Then some operations, such as image-increase-size, cause an error.

Example:
C-x C-f /emacs-27.1-x86_64/x86_64/share/emacs/27.1/etc/images/splash.png RET
M-: (point) RET
  => 3 ;; check current point
C-c C-c ;; change to text display
M-: (point) RET
  => 1 :: check current point
C-c C-c ;; change to image display
M-: (point) RET
  => 25161 ;; check current point, value is EOB
+ ;; image-increase-size
  -| Error running timer ‘image--change-size’: (error "No image under point")
r ;; image-rotate
  -| No image under point


In GNU Emacs 27.1 (build 1, x86_64-w64-mingw32)
 of 2020-08-22 built on CIRROCUMULUS
Repository revision: 86d8d76aa36037184db0b2897c434cdaab1a9ae8
Repository branch: HEAD
Windowing system distributor 'Microsoft Corp.', version 10.0.18363
System Description: Microsoft Windows 10 Pro (v10.0.1909.18363.1379)

Recent messages:

Configured using:
 'configure --without-dbus --host=x86_64-w64-mingw32
 --without-compress-install 'CFLAGS=-O2 -static''

Configured features:
XPM JPEG TIFF GIF PNG RSVG SOUND NOTIFY W32NOTIFY ACL GNUTLS LIBXML2
HARFBUZZ ZLIB TOOLKIT_SCROLL_BARS MODULES THREADS JSON PDUMPER LCMS2 GMP

Important settings:
  value of $LANG: JPN
  locale-coding-system: cp932

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  electric-indent-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
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort emacsbug sendmail mail-extr message rmc puny dired
dired-loaddefs format-spec rfc822 mml mml-sec password-cache epa derived
epg epg-config gnus-util rmail rmail-loaddefs text-property-search
time-date subr-x seq byte-opt gv bytecomp byte-compile cconv mm-decode
mm-bodies mm-encode mail-parse rfc2231 rfc2047 rfc2045 mm-util
ietf-drums mail-prsvr mailabbrev mail-utils gmm-utils mailheader cl-seq
image-mode exif term/bobcat help-mode easymenu cl-loaddefs cl-lib
japan-util tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel dos-w32 ls-lisp disp-table term/w32-win w32-win
w32-vars term/common-win tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode elisp-mode lisp-mode
prog-mode register page tab-bar menu-bar rfn-eshadow isearch timer
select scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame minibuffer 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 composite charscript charprop case-table epa-hook
jka-cmpr-hook help simple abbrev obarray 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 threads w32notify w32 lcms2 multi-tty make-network-process
emacs)

Memory information:
((conses 16 52863 8451)
 (symbols 48 6373 1)
 (strings 32 17684 1753)
 (string-bytes 1 552218)
 (vectors 16 11210)
 (vector-slots 8 213266 11242)
 (floats 8 33 39)
 (intervals 56 268 0)
 (buffers 1000 13))