bug#27335: 25.2; message.el message-insert-signature adds '-- ' line even if said line is in signature file

[Alessandro Costantini]

When I compose a message with C-x m the standard signature
block header:
'-- \n'
is inserted in the buffer even if message-signature-file
already contains it.
I think the code that does this is in message.el line 3630
My .signature file contains:
--
Alessandro Costantini




In GNU Emacs 25.2.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.22.10)
 of 2017-04-22 built on juergen
Windowing system distributor 'The X.Org Foundation', version 11.0.11903000
System Description:     Manjaro Linux

Configured using:
 'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --with-x-toolkit=gtk3 --with-xft --with-modules
 'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe
 -fstack-protector-strong' CPPFLAGS=-D_FORTIFY_SOURCE=2
 LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GCONF GSETTINGS
NOTIFY ACL GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 MODULES

Important settings:
  value of $LC_MONETARY: it_IT.UTF-8
  value of $LC_NUMERIC: it_IT.UTF-8
  value of $LC_TIME: it_IT.UTF-8
  value of $LANG: en_US.utf8
  locale-coding-system: utf-8-unix

Major mode: Emacs-Lisp

Minor modes in effect:
  diff-auto-refine-mode: t
  whitespace-mode: t
  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
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
Note: file is write protected
Mark set
Mark saved where search started
Mark set
Quit
Mark set
Quit
Mark saved where search started
Mark set [3 times]
<mouse-7> is undefined [2 times]

Load-path shadows:
None found.

Features:
(shadow sort emacsbug info mule-diag ruler-mode hl-line hexl eieio-opt
speedbar sb-image ezimage dframe rfc2104 network-stream nsm starttls tls
gnutls message idna rfc822 mml mml-sec epg mm-decode mm-bodies mm-encode
mail-parse rfc2231 mailabbrev gmm-utils mailheader mail-extr smtpmail
auth-source password-cache sendmail rfc2047 rfc2045 ietf-drums mm-util
mail-prsvr mail-utils help-fns debug sh-script smie executable conf-mode
misearch multi-isearch vc-git diff-mode org-rmail org-mhe org-irc
org-info org-gnus gnus-util org-docview doc-view subr-x jka-compr
image-mode org-bibtex bibtex org-bbdb org-w3m dired slime-fancy
slime-trace-dialog slime-fontifying-fu slime-package-fu slime-references
slime-compiler-notes-tree slime-scratch slime-presentations advice
bridge slime-macrostep macrostep slime-mdot-fu slime-enclosing-context
slime-fuzzy slime-fancy-trace slime-fancy-inspector slime-c-p-c
slime-editing-commands slime-autodoc slime-repl elp slime-parse slime
derived edmacro kmacro disp-table lisp-mnt gud apropos compile etags
xref cl-seq project eieio eieio-core arc-mode archive-mode pp hyperspec
cl-macs thingatpt browse-url cl slime-autoloads whitespace org org-macro
org-footnote org-pcomplete pcomplete org-list org-faces org-entities
noutline outline easy-mmode org-version ob-emacs-lisp ob ob-tangle
ob-ref ob-lob ob-table ob-exp org-src ob-keys ob-comint comint
ansi-color ring ob-core ob-eval org-compat org-macs org-loaddefs
format-spec find-func cal-menu calendar cal-loaddefs server finder-inf
package epg-config seq byte-opt gv bytecomp byte-compile cl-extra
help-mode easymenu cconv cl-loaddefs pcase cl-lib time-date mule-util
tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type
mwheel 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 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 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 move-toolbar gtk x-toolkit x
multi-tty make-network-process emacs)

Memory information:
((conses 16 318177 61678)
 (symbols 48 36103 0)
 (miscs 40 222 678)
 (strings 32 67882 8657)
 (string-bytes 1 2092134)
 (vectors 16 35261)
 (vector-slots 8 1491137 193443)
 (floats 8 367 539)
 (intervals 56 9688 90)
 (buffers 976 35))

-- 
-- 
Alessandro Costantini