bug#24627: 24.5; (thing-at-point 'list) may return a non-empty string without a list

[Tino Calancha <tino.calancha@gmail.com>]

From: Tino Calancha <tino.calancha@gmail.com>
To: bug-gnu-emacs@gnu.org
Subject: 24.5; (thing-at-point 'list) make return a non-empty string without a list
--text follows this line--

emacs -Q thingatpt.el
> C-p
M-: (thing-at-point 'list t) RET

=> ";;; thingatpt.el ends here\n"

(list-at-point) returns nil as it should.
Same behavior in master branch.

In GNU Emacs 24.5.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.20.5)
  of 2016-06-02 on calancha-pc
Windowing system distributor `The X.Org Foundation', version 11.0.11804000
System Description:	Debian GNU/Linux testing (stretch)

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

Major mode: Emacs-Lisp

Minor modes in effect:
   tooltip-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

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Mark set
";;; thingatpt.el ends here
"

Load-path shadows:
None found.

Features:
(shadow sort gnus-util mail-extr emacsbug message format-spec rfc822 mml
easymenu mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums
mm-util help-fns mail-prsvr mail-utils thingatpt time-date tooltip
electric uniquify ediff-hook vc-hooks lisp-float-type mwheel x-win x-dnd
tool-bar dnd fontset image regexp-opt fringe tabulated-list newcomment
lisp-mode prog-mode register page menu-bar rfn-eshadow timer select
scroll-bar mouse jit-lock font-lock syntax facemenu font-core frame cham
georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese hebrew greek romanian slovak czech european ethiopic
indian cyrillic chinese case-table epa-hook jka-cmpr-hook help simple
abbrev minibuffer 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 make-network-process
dbusbind gfilenotify dynamic-setting system-font-setting
font-render-setting move-toolbar gtk x-toolkit x multi-tty emacs)

Memory information:
((conses 16 72272 4417)
  (symbols 48 17618 0)
  (miscs 40 40 138)
  (strings 32 9497 4205)
  (string-bytes 1 260150)
  (vectors 16 8998)
  (vector-slots 8 384193 16741)
  (floats 8 64 85)
  (intervals 56 290 1)
  (buffers 960 12)
  (heap 1024 9017 976))