bug#24781: 26.0.50; fill-paragraph, in message-mode, behaves badly

[bugs@gnu.support (Jean Louis)]

When I turn on message-mode, and try M-q, the paragraph does not intend
well. The second line gets TAB in beginning, and there are no following
comments from second line further.

I can reproduce it each time when I open new file with message-mode, but
not in this buffer. And I was testing it with -Q and without site
settings. In this buffer, it is working.



In GNU Emacs 26.0.50.3 (x86_64-unknown-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2016-10-21 built on protected.rcdrun.com
Repository revision: 76b08a35bb6b3b32e5e5fda53e374769ceae6ed8
Windowing system distributor 'The X.Org Foundation', version 11.0.11801000
Recent messages:
Quit
Mark set [2 times]
Sending...
Mark set [2 times]
Sending via mail...
Setting ‘send-mail-function’ temporarily since "emacs -q" would overwrite customizations
Sending...done
Making completion list...
Quit
Type "q" in help window to restore its previous buffer, C-M-v to scroll help.
Quit
Configured using:
 'configure --prefix=/usr --localstatedir=/var --with-sound=alsa
 --with-modules --with-x --with-x-toolkit=lucid'

Configured features:
XAW3D XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND DBUS GCONF GSETTINGS
NOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE XFT ZLIB
TOOLKIT_SCROLL_BARS LUCID X11 MODULES

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

Major mode: Fundamental

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

Load-path shadows:
/usr/share/emacs/site-lisp/t-mouse hides /usr/share/emacs/26.0.50/lisp/t-mouse

Features:
(shadow help-fns radix-tree emacsbug mailalias cus-edit cus-start
cus-load wid-edit sendmail sort mail-extr message subr-x puny seq
byte-opt gv bytecomp byte-compile cl-extra help-mode cconv cl-loaddefs
pcase cl-lib dired dired-loaddefs format-spec rfc822 mml easymenu
mml-sec password-cache epa derived epg epg-config gnus-util rmail
rmail-loaddefs mm-decode mm-bodies mm-encode mail-parse rfc2231 rfc2047
rfc2045 mm-util ietf-drums mail-prsvr mailabbrev mail-utils gmm-utils
mailheader time-date mule-util tooltip eldoc electric uniquify
ediff-hook vc-hooks lisp-float-type mwheel term/x-win 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 term/tty-colors 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 x-toolkit x multi-tty
make-network-process emacs)

Memory information:
((conses 16 119006 13464)
 (symbols 48 21872 0)
 (miscs 40 106 203)
 (strings 32 22283 4346)
 (string-bytes 1 668542)
 (vectors 16 15168)
 (vector-slots 8 465884 9745)
 (floats 8 203 191)
 (intervals 56 401 0)
 (buffers 976 16)
 (heap 1024 20939 2478))