bug#26298: 26.0.50; Gnus fails to sign mail with PGP

[Torsten Bronger]

If I sign an email with C-c RET s o and try to send it, Emacs aborts
with the following backtrace:

Debugger entered--Lisp error: (wrong-type-argument char-or-string-p nil)
  mml1991-epg-sign((part (sign . "pgp") (tag-location . 845) (contents . 
"asdsd\n-- \nTorsten Bronger\n")))
  mml1991-sign((part (sign . "pgp") (tag-location . 845) (contents . "asdsd\n-- 
\nTorsten Bronger\n")))
  (or (mml1991-sign cont) (error "Signing failed... inspect message logs for 
errors"))
  mml-pgp-sign-buffer((part (sign . "pgp") (tag-location . 845) (contents . 
"asdsd\n-- \nTorsten Bronger\n")))
  mml-generate-mime-1((part (sign . "pgp") (tag-location . 845) (contents . 
"asdsd\n-- \nTorsten Bronger\n")))
  mml-generate-mime()
  message-encode-message-body()
  message-send-mail(nil)
  message-send-via-mail(nil)
  message-send(nil)
  message-send-and-exit(nil)
  funcall-interactively(message-send-and-exit nil)
  call-interactively(message-send-and-exit nil nil)
  command-execute(message-send-and-exit)



In GNU Emacs 26.0.50.1 (x86_64-pc-linux-gnu)
 of 2017-03-20 built on wilson
Repository revision: 09d50834206ff48bf6ac214e8cfb31d281ba993c
Windowing system distributor 'The X.Org Foundation', version 11.0.11804000
System Description:     Ubuntu 16.04.1 LTS

Recent messages:
Sending...
Mark set [2 times]
Entering debugger...
Auto-saving...done
Quit [4 times]
Making completion list...
Quit
Mark set
next-line: End of buffer [2 times]
Making completion list...

Configured using:
 'configure --prefix=/usr/local/ --mandir=/usr/local/share/man/
 --infodir=/usr/local/share/info/ --with-x-toolkit=no --without-makeinfo
 --with-xpm --with-jpeg --with-tiff --with-gif --with-png --with-x'

Configured features:
XPM JPEG TIFF GIF PNG RSVG SOUND DBUS GSETTINGS NOTIFY GNUTLS LIBXML2
FREETYPE XFT ZLIB X11

Important settings:
  value of $EMACSLOADPATH: /home/bronger/.emacs.d/lisp:
  value of $LANG: de_DE.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Debugger

Minor modes in effect:
  diff-auto-refine-mode: t
  global-auto-revert-mode: t
  shell-dirtrack-mode: t
  savehist-mode: t
  desktop-save-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  line-number-mode: t

Load-path shadows:
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/home/bronger/.emacs.d/lisp/nxhtml/related/visual-basic-mode
/home/bronger/.emacs.d/lisp/yasnippet/snippets/fundamental-mode/.yas-setup 
hides /home/bronger/.emacs.d/lisp/yasnippet/snippets/prog-mode/.yas-setup
/home/bronger/.emacs.d/lisp/yasnippet/snippets/fundamental-mode/.yas-setup 
hides /home/bronger/.emacs.d/lisp/yasnippet/snippets/python-mode/.yas-setup
/home/bronger/.emacs.d/lisp/yasnippet/snippets/fundamental-mode/.yas-setup 
hides 
/home/bronger/.emacs.d/lisp/yasnippet/yasmate/snippets/html-mode/.yas-setup
/home/bronger/.emacs.d/lisp/yasnippet/snippets/fundamental-mode/.yas-setup 
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/home/bronger/.emacs.d/lisp/yasnippet/yasmate/snippets/html-mode/.yasmate-extra-substitutions
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/home/bronger/.emacs.d/lisp/yasnippet/yasmate/snippets/rails-mode/.yasmate-extra-substitutions
/home/bronger/.emacs.d/lisp/yasnippet/snippets/fundamental-mode/.yas-setup 
hides 
/home/bronger/.emacs.d/lisp/yasnippet/yasmate/snippets/rails-mode/.yas-setup
/home/bronger/.emacs.d/lisp/yasnippet/yasmate/snippets/html-mode/.yasmate-extra-substitutions
 hides 
/home/bronger/.emacs.d/lisp/yasnippet/yasmate/snippets/ruby-mode/.yasmate-extra-substitutions
/home/bronger/.emacs.d/lisp/yasnippet/snippets/fundamental-mode/.yas-setup 
hides 
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/usr/local/share/emacs/site-lisp/w3m/w3m-fb

Features:
(shadow emacsbug sendmail misearch multi-isearch eieio-opt speedbar
sb-image ezimage dframe help-fns radix-tree debug mml1991 nnir
gnus-picon sort smiley gnus-cite gnus-async gnus-bcklg gnus-draft
gnus-ml disp-table nndraft nnmh gnus-agent gnus-srvr gnus-score
score-mode nnvirtual gnus-msg nnml nnfolder gnus-cache bbdb-gnus
bbdb-snarf mail-extr bbdb-com warnings network-stream nsm starttls nntp
gnus-topic add-log gmane gnus-art mm-uu mml2015 mm-view mml-smime smime
dig gnus-sum gnus-group gnus-undo gnus-start gnus-cloud nnimap nnmail
mail-source tls gnutls utf7 netrc nnoo gnus-spec gnus-int gnus-range
message rfc822 mml mml-sec epa epg mm-decode mm-bodies mm-encode
mail-parse rfc2231 mailabbrev gmm-utils mailheader gnus-win vc-cvs
go-oracle flyspell ispell conf-mode js moz imenu cc-mode cc-fonts
cc-guess cc-menus cc-cmds cc-styles cc-align cc-engine cc-vars cc-defs
css-mode eww puny mm-url gnus nnheader url-queue shr svg rng-xsd
xsd-regexp rng-cmpct rng-nxml rng-valid rng-loc rng-uri rng-parse
nxml-parse rng-match rng-dt rng-util rng-pttrn nxml-ns nxml-mode
nxml-outln nxml-rap sgml-mode dom nxml-util nxml-enc xmltok hideshow
dired-aux reftex-dcr reftex reftex-loaddefs reftex-vars font-latex
latexenc vc-git diff-mode python tramp-sh json map darkroom cql-mode sql
view rust-mode swift-mode go-errcheck go-mode url url-proxy url-privacy
url-expand url-methods url-history url-cookie url-domsuf url-util
mailcap find-file ffap thingatpt etags xref project yaml-mode
dockerfile-mode derived rx sh-script smie executable dired-x
adaptive-wrap vc-dispatcher vc-bzr org-element org-rmail org-mhe org-irc
org-info org-gnus gnus-util rmail rmail-loaddefs rfc2047 rfc2045
ietf-drums mail-utils org-docview org-bibtex bibtex org-bbdb org-w3m
org-agenda ob-python org org-macro org-footnote org-pcomplete org-list
org-faces org-entities noutline outline org-version ob-emacs-lisp ob
ob-tangle ob-ref ob-lob ob-table ob-exp org-src ob-keys ob-comint
ob-core ob-eval org-compat org-macs org-loaddefs find-func server w3m
browse-url doc-view subr-x jka-compr dired dired-loaddefs image-mode
w3m-hist w3m-fb bookmark-w3m w3m-ems wid-edit w3m-ccl ccl w3m-favicon
w3m-image w3m-proc w3m-util rst compile browse-kill-ring mmm-mode
mmm-univ mmm-class mmm-region mmm-auto mmm-vars mmm-utils mmm-compat cl
bbdb-autoloads bbdb timezone cal-china lunar solar cal-dst cal-bahai
cal-islam cal-hebrew holidays hol-loaddefs appt diary-lib diary-loaddefs
cal-menu calendar cal-loaddefs preview prv-emacs info reporter latex
easy-mmode tex-style tex-buf tex dbus xml mm-util mail-prsvr autorevert
filenotify preview-latex tex-site auto-loads edmacro kmacro tramp
tramp-compat tramp-loaddefs trampver ucs-normalize shell pcomplete
comint ansi-color ring parse-time format-spec advice savehist desktop
frameset delsel cus-start cus-load finder-inf package epg-config
url-handlers url-parse auth-source cl-seq eieio eieio-core cl-macs
eieio-loaddefs password-cache url-vars 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 term/x-win x-win term/common-win x-dnd tool-bar
dnd fontset image regexp-opt fringe tabulated-list replace newcomment
text-mode elisp-mode lisp-mode prog-mode register page menu-bar
rfn-eshadow isearch 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 composite 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 multi-tty
make-network-process emacs)

Memory information:
((conses 16 871277 112392)
 (symbols 48 136658 1)
 (miscs 40 8775 673)
 (strings 32 201286 28052)
 (string-bytes 1 6150598)
 (vectors 16 80569)
 (vector-slots 8 1398799 46356)
 (floats 8 1890 586)
 (intervals 56 27999 212)
 (buffers 976 407)
 (heap 1024 99104 3681))

-- 
Torsten Bronger