bug#58091: 28.2.50; Unexpected thing-at-point URL in eww input field

["Basil L. Contovounesios" via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

I see the following in Emacs 28 and 29 but not in 27 or 26:

0. emacs -Q
1. M-x eww RET https://gnu.org/cgi-bin/estseek.cgi RET
2. TAB TAB
   [Point is now in the input field.]
3. M-: (thing-at-point 'url) RET

This gives:

  (input
   ((type . "text")
    (name . "phrase")
    (value . "")
    (size . "80")
    (id . "phrase")
    (class . "text")
    (tabindex . "1")
    (accesskey . "0")))

Whereas I'd expect a string or nil.

-- 
Basil

In GNU Emacs 28.2.50 (build 1, x86_64-pc-linux-gnu, X toolkit, cairo version 1.16.0, Xaw3d scroll bars)
 of 2022-09-13 built on tia
Repository revision: 2cdb9d03fd28138f079cfe5c788d860beb9ea7c2
Repository branch: wt/emacs-28
Windowing system distributor 'The X.Org Foundation', version 11.0.12101004
System Description: Debian GNU/Linux bookworm/sid

Configured using:
 'configure 'CFLAGS=-O0 -ggdb3' --prefix=/home/blc/.local
 --program-suffix=-28 --enable-checking=yes,glyphs
 --enable-check-lisp-object-type --with-file-notification=yes
 --with-x-toolkit=lucid --with-x'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES NOTIFY
INOTIFY PDUMPER PNG RSVG SECCOMP SOUND THREADS TIFF TOOLKIT_SCROLL_BARS
X11 XAW3D XDBE XIM XPM LUCID ZLIB

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

Major mode: eww

Minor modes in effect:
  tooltip-mode: t
  global-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
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message dired dired-loaddefs rfc822 mml
mml-sec epa derived epg rfc6068 epg-config mm-decode mm-bodies mm-encode
mailabbrev gmm-utils mailheader sendmail cl-extra help-mode gnutls
network-stream url-http mail-parse rfc2231 url-gw nsm rmc url-cache
url-auth format-spec eww xdg url-queue thingatpt shr kinsoku svg xml dom
browse-url url url-proxy url-privacy url-expand url-methods url-history
url-cookie url-domsuf url-util url-parse url-vars mailcap puny mm-url
gnus nnheader gnus-util rmail rmail-loaddefs auth-source cl-seq eieio
eieio-core cl-macs eieio-loaddefs password-cache json map rfc2047
rfc2045 ietf-drums text-property-search time-date subr-x seq byte-opt gv
bytecomp byte-compile cconv mail-utils wid-edit mm-util mail-prsvr
cl-loaddefs cl-lib iso-transl tooltip eldoc paren electric uniquify
ediff-hook vc-hooks lisp-float-type elisp-mode mwheel term/x-win x-win
term/common-win x-dnd 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 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 emoji-zwj charscript charprop case-table epa-hook
jka-cmpr-hook help simple abbrev obarray cl-preloaded nadvice button
loaddefs faces cus-face macroexp files window text-properties overlay
sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote threads dbusbind inotify lcms2
dynamic-setting system-font-setting font-render-setting cairo x-toolkit
x multi-tty make-network-process emacs)

Memory information:
((conses 16 94068 7222)
 (symbols 48 9746 1)
 (strings 32 35817 1941)
 (string-bytes 1 1012544)
 (vectors 16 17290)
 (vector-slots 8 228372 9374)
 (floats 8 49 42)
 (intervals 56 311 0)
 (buffers 992 13))