bug#77854: 31.0.50; eww-list-buffers replaces other buffers' contents

[William Wen]

For some reason, eww-list-buffers keeps trying to replace the contents
of different buffers with the contents of its own buffer. Here's how to
reproduce on master with emacs -Q:

1. M-x eww to any URL
2. M-x eww-list-buffers
3. Open any file
4. M-x revert-buffer on that file's buffer

You should see the contents of eww-list-buffers rather than the contents
of your file.

In GNU Emacs 31.0.50 (build 4, x86_64-pc-linux-gnu, GTK+ Version
 3.24.38, cairo version 1.16.0) of 2025-04-16 built on Will_Laptop
Repository revision: 4532fbefece210061d01ab9523f3054aadb1c45a
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 
11.0.12101007
System Description: Debian GNU/Linux 12 (bookworm)

Configured using:
 'configure --with-native-compilation=aot --without-compress-install'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES NATIVE_COMP
NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP SOUND SQLITE3 THREADS TIFF
TOOLKIT_SCROLL_BARS WEBP X11 XDBE XIM XINERAMA XINPUT2 XPM XRANDR GTK3
ZLIB

Important settings:
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Shell-script

Minor modes in effect:
  sh-electric-here-document-mode: t
  vtable-header-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  show-paren-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
  minibuffer-regexp-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr compile comint ansi-osc ansi-color ring shortdoc
help-fns radix-tree emacsbug lisp-mnt message yank-media dired
dired-loaddefs rfc822 mml mml-sec epa derived epg rfc6068 epg-config
mm-decode mm-bodies mm-encode mailabbrev gmm-utils mailheader sendmail
vc-git diff-mode track-changes easy-mmode files-x vc-dispatcher
sh-script smie treesit executable textsec uni-scripts idna-mapping
ucs-normalize uni-confusable textsec-check cl-extra help-mode gnutls
network-stream url-http mail-parse rfc2231 rfc2047 rfc2045 ietf-drums
url-gw nsm url-cache url-auth format-spec comp-run comp-common rx eww
vtable mule-util url-queue thingatpt shr pixel-fill kinsoku url-file svg
xml dom browse-url xdg url url-proxy url-privacy url-expand url-methods
url-history url-cookie generate-lisp-file url-domsuf url-util url-parse
auth-source cl-seq eieio eieio-core cl-macs icons password-cache json
map byte-opt gv bytecomp byte-compile url-vars mailcap puny mm-url gnus
nnheader gnus-util text-property-search time-date subr-x mail-utils
range wid-edit mm-util mail-prsvr cl-loaddefs cl-lib rmc iso-transl
tooltip cconv eldoc paren electric uniquify ediff-hook vc-hooks
lisp-float-type elisp-mode mwheel term/x-win x-win term/common-win x-dnd
touch-screen tool-bar dnd fontset image regexp-opt fringe tabulated-list
replace newcomment text-mode lisp-mode prog-mode register page tab-bar
menu-bar rfn-eshadow isearch easymenu timer select scroll-bar mouse
jit-lock font-lock syntax font-core term/tty-colors frame minibuffer
nadvice seq simple cl-generic indonesian philippine 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 emoji-zwj charscript charprop
case-table epa-hook jka-cmpr-hook help abbrev obarray oclosure
cl-preloaded button loaddefs theme-loaddefs faces cus-face macroexp
files window text-properties overlay sha1 md5 base64 format env
code-pages mule custom widget keymap hashtable-print-readable backquote
threads dbusbind inotify lcms2 dynamic-setting system-font-setting
font-render-setting cairo gtk x-toolkit xinput2 x multi-tty move-toolbar
make-network-process tty-child-frames native-compile emacs)

Memory information:
((conses 16 321038 24441) (symbols 48 13070 1) (strings 32 62228 2624)
 (string-bytes 1 1828116) (vectors 16 47323)
 (vector-slots 8 669641 20596) (floats 8 227 21) (intervals 56 2412 0)
 (buffers 984 17))