bug#35130: 27.0.50; gnus cannot save

[James Cloos]

As of master commit 39c0795ef2d592d4632516ee57f1cf51a2159608 gnus is
unable to save.

The error (w/ debug-on-error t) is:

Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil)
  gnus-gnus-to-newsrc-format()
  gnus-save-newsrc-file(nil)
  gnus-group-save-newsrc(nil)
  funcall-interactively(gnus-group-save-newsrc nil)
  call-interactively(gnus-group-save-newsrc nil nil)
  command-execute(gnus-group-save-newsrc)

I also got that error a few times while trying to sort the *Group*
buffer, but then that started working.

Saving has not started working.

At a quick look of the recent history, commits
a09306d53ba86b4596219b2be723659f7c0f2669 and
a8efdd4c62fbf9c275a57f71cc8a3ca845ad3b1f look relevant.


In GNU Emacs 27.0.50 (build 1, x86_64-pc-linux-gnu, X toolkit, Xaw3d scroll 
bars)
 of 2019-04-03 built on carbon.jhcloos.org
Repository revision: 39c0795ef2d592d4632516ee57f1cf51a2159608
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.11699901
System Description: Gentoo/Linux

Recent messages:
Proceeding, will debug on next eval or call.
Entering debugger...
Proceeding, will debug on next eval or call.
Entering debugger...
Continuing.
Entering debugger...
Continuing.
Entering debugger...
Continuing.
Auto-saving...

Configured using:
 'configure --prefix=/usr --build=x86_64-pc-linux-gnu
 --host=x86_64-pc-linux-gnu --mandir=/usr/share/man
 --infodir=/usr/share/info --datadir=/usr/share --sysconfdir=/etc
 --localstatedir=/var/lib --disable-silent-rules
 --docdir=/usr/share/doc/emacs-vcs-27.0.9999
 --htmldir=/usr/share/doc/emacs-vcs-27.0.9999/html --libdir=/usr/lib64
 --program-suffix=-emacs-27-vcs --includedir=/usr/include/emacs-27-vcs
 --infodir=/usr/share/info/emacs-27-vcs --localstatedir=/var
 --enable-locallisppath=/etc/emacs:/usr/share/emacs/site-lisp
 --without-compress-install --without-hesiod --without-pop
 --with-file-notification=inotify --enable-acl --with-dbus
 --without-modules --with-gameuser=:gamestat --with-gpm --with-json
 --with-kerberos --with-kerberos5 --with-lcms2 --with-xml2
 --without-mailutils --without-selinux --with-gnutls
 --without-libsystemd --with-threads --without-wide-int --with-zlib
 --with-sound=alsa --with-x --without-ns --without-gconf --with-libgmp
 --without-gsettings --with-toolkit-scroll-bars --with-gif --with-jpeg
 --with-png --with-rsvg --with-tiff --with-xpm --with-imagemagick
 --with-xft --without-cairo --with-libotf --with-m17n-flt
 --with-x-toolkit=lucid --with-xaw3d 'CFLAGS=-pipe -O2 -g3
 -march=native' CPPFLAGS= LDFLAGS=-Wl,-O1'

Configured features:
XAW3D XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GLIB NOTIFY
INOTIFY ACL GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS LUCID X11 XDBE XIM THREADS JSON PDUMPER LCMS2 GMP

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

Major mode: Group

Minor modes in effect:
  gnus-undo-mode: t
  show-paren-mode: t
  display-time-mode: t
  shell-dirtrack-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  file-name-shadow-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
  column-number-mode: t
  line-number-mode: t

Load-path shadows:
/usr/share/emacs/site-lisp/graphviz-dot-mode/graphviz-dot-mode hides 
/home/cloos/elisp/graphviz-dot-mode
/usr/share/emacs/site-lisp/git/git hides /home/cloos/elisp/git
/usr/share/emacs/site-lisp/git/git-blame hides /home/cloos/elisp/git-blame
/usr/share/emacs/site-lisp/fricas/fricas hides /home/cloos/elisp/fricas
/usr/share/emacs/site-lisp/auctex/context hides /home/cloos/elisp/context
/home/cloos/elisp/json hides /usr/share/emacs/27.0.50/lisp/json
/home/cloos/elisp/doc-view hides /usr/share/emacs/27.0.50/lisp/doc-view

Features:
(shadow emacsbug two-column iso-transl macros kmacro misearch
multi-isearch cl-print cus-edit help-fns radix-tree flow-fill sendmail
gnus-fun nnir qp cl-extra sort url-util shr-color color shr svg xml dom
gnus-cite mm-archive mail-extr face-remap gnus-async quilt gnus-kill
gnus-ml disp-table nndraft nnmh utf-7 nnml gnutls nnmaildir vc-filewise
vc-rcs network-stream nsm gnus-agent gnus-srvr gnus-score score-mode
nnvirtual gnus-msg gnus-art mm-uu mml2015 mm-view mml-smime smime dig
mailcap nntp gnus-cache gnus-sum gnus-group gnus-undo gnus-start
gnus-cloud nnimap nnmail mail-source utf7 netrc nnoo gnus-spec gnus-int
gnus-range message rmc puny dired dired-loaddefs rfc822 mml mml-sec epa
derived epg mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev
gmm-utils mailheader gnus-win gnus nnheader gnus-util rmail
rmail-loaddefs rfc2047 rfc2045 ietf-drums text-property-search time-date
mail-utils wid-edit elec-pair jka-compr mm-util mail-prsvr paren time
delsel cus-start cus-load jhc-backend-xft-fonts w3m-load preview-latex
mmm-auto mmm-vars mmm-compat ido ess-toolbar ess-mouse mouseme thingatpt
browse-url ess-swv ess-noweb ess-noweb-font-lock-mode ess-bugs-l
ess-sas-d ess-sas-l ess-sas-a ess-stata-mode ess-stata-lang cc-vars
cc-defs make-regexp essd-els ess-sp6-d ess-dde ess-sp3-d ess-julia
julia-mode ert pp ewoc debug backtrace help-mode find-func ess-r-mode
ess-r-package ess-r-syntax ess-r-completion ess-roxy essddr ess-rd
noutline outline easy-mmode hideshow ess-s-lang ess-help ess ess-mode
ess-noweb-mode ess-inf ess-tracebug compile tramp tramp-loaddefs
trampver tramp-integration files-x tramp-compat ucs-normalize shell
pcomplete comint ansi-color ring parse-time format-spec advice
ess-generics cl ess-custom executable ess-compat ess-utils ess-site
bbdb-loaddefs auto-loads tex-site finder-inf package easymenu epg-config
url-handlers url-parse auth-source cl-seq eieio eieio-core cl-macs
eieio-loaddefs password-cache json subr-x map url-vars seq byte-opt gv
bytecomp byte-compile cconv cl-loaddefs cl-lib 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 charprop 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 threads dbusbind inotify lcms2 dynamic-setting
font-render-setting x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 4468393 10534538)
 (symbols 48 31753 855)
 (strings 32 573556 221935)
 (string-bytes 1 20861193)
 (vectors 16 60725)
 (vector-slots 8 1473206 158906)
 (floats 8 431 504)
 (intervals 56 5852 779)
 (buffers 992 52))