bug#46019: 27.1.90; gnus-group-list improperly sorted, drops meaningful group

[Juan José García Ripoll]

The problem:

- On a running Gnus instance, the list of groups in gnus-group-list is
  not properly sorted: dummy.group gets close to the end.

Symptoms:

- As a result, the first group in the list is never shown, except when
  going to the server list

Steps to reproduce:

In my site, a simple configuration to poll an IMAP server shows the
problem. This configuration is stored in launcher.el and ran with
"emacs -Q -l launcher.el"

(require 'gnus)
;; Passwords for my server
(setq auth-sources '("~/OneDrive/Library/dot.authinfo.gpg"))
(epg-find-configuration 'OpenPGP)
;; Save configuration elsewhere, not to clobber my system
(setq gnus-directory "~/tmp/")
(setq gnus-startup-file (expand-file-name ".newsrc" gnus-directory))
(setq gnus-select-method '(nnnil ""))
(setq gnus-secondary-select-methods
      '((nnimap "work"
                (nnimap-address "work.imap.server.com")
                (nnimap-server-port 993)
                (nnimap-stream ssl)
                (nnimap-fetch-partial-articles t))))
(gnus)
(print gnus-group-list)

What happens:

- Emacs outputs a list of groups that begins with "nnimap+work:Trash",
  with dummy.group close to the end

("nnimap+work:Trash" "nnimap+work:Archive" ... "dummy.group" "nndraft:drafts")

- When pressing 'L' to get the list of groups, Trash is removed, due to
  the code in gnus-group-prepare-flat

(defun gnus-group-prepare-flat (level &optional predicate lowest regexp)
 ...
      ;; List living groups, according to order in `gnus-group-list'.
      (dolist (g (cdr gnus-group-list))
        (setq info (gnus-get-info g)
              group (gnus-info-group info)

What should happen:

- The list of groups should remain sorted, with dummy.group at the
  beginning


In GNU Emacs 27.1.90 (build 1, x86_64-w64-mingw32)
Repository revision: 37eba74d609c74bcf9ac3c481a29377913783ac4
Repository branch: HEAD
Windowing system distributor 'Microsoft Corp.', version 10.0.19042
System Description: Microsoft Windows 10 Pro (v10.0.2009.19042.746)

Recent messages:
Mark set [2 times]
Auto-saving...done
Mark set
Auto-saving...done
Sending...
Sending news via news.gmane.io using nntp...
Saving file c:/Users/juanj/OneDrive/Mail/archive/sent/2021-01...
Wrote c:/Users/juanj/OneDrive/Mail/archive/sent/2021-01
Sending...done
Making completion list... [2 times]

Configured using:
 'configure
 --prefix=/c/Users/juanj/src/emacs-build/pkg/emacs-27_1_90-x86_64
 --with-zlib --with-gnutls --with-xml2 --with-lcms2 --with-json
 --with-harfbuzz --with-cairo --with-rsvg --with-png --with-gif
 --with-tiff --with-jpeg --with-xpm --disable-build-details
 --disable-silent-rules --without-dbus'

Configured features:
XPM JPEG TIFF GIF PNG RSVG SOUND NOTIFY W32NOTIFY ACL GNUTLS LIBXML2
HARFBUZZ ZLIB TOOLKIT_SCROLL_BARS MODULES THREADS JSON PDUMPER LCMS2 GMP

Important settings:
  value of $LANG: ESN
  locale-coding-system: cp1252

Major mode: Article

Minor modes in effect:
  shell-dirtrack-mode: t
  display-time-mode: t
  icomplete-vertical-mode: t
  save-place-mode: t
  savehist-mode: t
  gcmh-mode: t
  override-global-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
  temp-buffer-resize-mode: t
  buffer-read-only: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
c:/Users/juanj/OneDrive/Library/Emacs/elpa-27/pdf-tools-0.90/pdf-virtual hides 
c:/Users/juanj/scoop/apps/emacs/current/share/emacs/site-lisp/pdf-tools/pdf-virtual
c:/Users/juanj/OneDrive/Library/Emacs/elpa-27/pdf-tools-0.90/pdf-view hides 
c:/Users/juanj/scoop/apps/emacs/current/share/emacs/site-lisp/pdf-tools/pdf-view
c:/Users/juanj/OneDrive/Library/Emacs/elpa-27/pdf-tools-0.90/pdf-util hides 
c:/Users/juanj/scoop/apps/emacs/current/share/emacs/site-lisp/pdf-tools/pdf-util
c:/Users/juanj/OneDrive/Library/Emacs/elpa-27/pdf-tools-0.90/pdf-tools hides 
c:/Users/juanj/scoop/apps/emacs/current/share/emacs/site-lisp/pdf-tools/pdf-tools
c:/Users/juanj/OneDrive/Library/Emacs/elpa-27/pdf-tools-0.90/pdf-sync hides 
c:/Users/juanj/scoop/apps/emacs/current/share/emacs/site-lisp/pdf-tools/pdf-sync
c:/Users/juanj/OneDrive/Library/Emacs/elpa-27/pdf-tools-0.90/pdf-outline hides 
c:/Users/juanj/scoop/apps/emacs/current/share/emacs/site-lisp/pdf-tools/pdf-outline
c:/Users/juanj/OneDrive/Library/Emacs/elpa-27/pdf-tools-0.90/pdf-occur hides 
c:/Users/juanj/scoop/apps/emacs/current/share/emacs/site-lisp/pdf-tools/pdf-occur
c:/Users/juanj/OneDrive/Library/Emacs/elpa-27/pdf-tools-0.90/pdf-misc hides 
c:/Users/juanj/scoop/apps/emacs/current/share/emacs/site-lisp/pdf-tools/pdf-misc
c:/Users/juanj/OneDrive/Library/Emacs/elpa-27/pdf-tools-0.90/pdf-loader hides 
c:/Users/juanj/scoop/apps/emacs/current/share/emacs/site-lisp/pdf-tools/pdf-loader
c:/Users/juanj/OneDrive/Library/Emacs/elpa-27/pdf-tools-0.90/pdf-links hides 
c:/Users/juanj/scoop/apps/emacs/current/share/emacs/site-lisp/pdf-tools/pdf-links
c:/Users/juanj/OneDrive/Library/Emacs/elpa-27/pdf-tools-0.90/pdf-isearch hides 
c:/Users/juanj/scoop/apps/emacs/current/share/emacs/site-lisp/pdf-tools/pdf-isearch
c:/Users/juanj/OneDrive/Library/Emacs/elpa-27/pdf-tools-0.90/pdf-info hides 
c:/Users/juanj/scoop/apps/emacs/current/share/emacs/site-lisp/pdf-tools/pdf-info
c:/Users/juanj/OneDrive/Library/Emacs/elpa-27/pdf-tools-0.90/pdf-history hides 
c:/Users/juanj/scoop/apps/emacs/current/share/emacs/site-lisp/pdf-tools/pdf-history
c:/Users/juanj/OneDrive/Library/Emacs/elpa-27/pdf-tools-0.90/pdf-dev hides 
c:/Users/juanj/scoop/apps/emacs/current/share/emacs/site-lisp/pdf-tools/pdf-dev
c:/Users/juanj/OneDrive/Library/Emacs/elpa-27/pdf-tools-0.90/pdf-cache hides 
c:/Users/juanj/scoop/apps/emacs/current/share/emacs/site-lisp/pdf-tools/pdf-cache
c:/Users/juanj/OneDrive/Library/Emacs/elpa-27/pdf-tools-0.90/pdf-annot hides 
c:/Users/juanj/scoop/apps/emacs/current/share/emacs/site-lisp/pdf-tools/pdf-annot

Features:
(shadow warnings emacsbug cus-start cus-load smtpmail mm-archive
gnus-topic nnfolder canlock vc-git diff-mode mailalias sendmail bbdb-mua
bbdb-com crm bbdb bbdb-site timezone mule-util sort smiley gnus-cite
mail-extr gnus-async gnus-bcklg eieio-opt speedbar sb-image ezimage
dframe qp gnus-ml dash help-fns radix-tree misearch multi-isearch
gnus-demon utf-7 nndraft nnmh epa-file gnutls network-stream nsm nnml
nnnil gnus-agent gnus-srvr gnus-score score-mode nnvirtual gnus-msg
gnus-art mm-uu mml2015 mm-view mml-smime smime dig nntp gnus-cache
bookmark pp tabify org-datetree face-remap org-indent org-element
avl-tree generator ol-eww eww mm-url thingatpt url-queue ol-rmail ol-mhe
ol-irc ol-info ol-gnus nnir gnus-sum url url-proxy url-privacy
url-expand url-methods url-history shr url-cookie url-domsuf url-util
svg xml dom gnus-group gnus-undo gnus-start gnus-cloud nnimap nnmail
mail-source utf7 netrc nnoo gnus-spec gnus-int gnus-range message rmc
puny 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 mail-utils mm-util mail-prsvr wid-edit ol-docview
doc-view jka-compr image-mode exif dired dired-loaddefs ol-bibtex bibtex
ol-bbdb ol-w3m org-capture org-refile org org-macro org-footnote
org-pcomplete org-list org-faces org-entities noutline outline
org-version ob-python python tramp-sh tramp tramp-loaddefs trampver
tramp-integration files-x tramp-compat shell pcomplete parse-time
iso8601 ob ob-tangle org-src ob-ref ob-lob ob-table ob-exp ob-comint
comint ansi-color ring ob-emacs-lisp ob-core ob-eval org-table ol
org-keys org-compat org-macs org-loaddefs format-spec time-date time
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 benchmark-init-modes debug backtrace find-func mailcap
icomplete-vertical icomplete epg-config modus-operandi-theme saveplace
savehist edmacro kmacro benchmark-init advice gcmh diminish cl-extra
help-mode use-package use-package-ensure use-package-delight
use-package-diminish use-package-bind-key bind-key easy-mmode
use-package-core finder-inf tex-site info package easymenu browse-url
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 tooltip eldoc electric
uniquify ediff-hook vc-hooks lisp-float-type mwheel dos-w32 ls-lisp
disp-table term/w32-win w32-win w32-vars term/common-win tool-bar dnd
fontset image regexp-opt fringe tabulated-list replace newcomment
text-mode elisp-mode lisp-mode prog-mode register page tab-bar menu-bar
rfn-eshadow isearch timer select scroll-bar mouse jit-lock font-lock
syntax facemenu font-core term/tty-colors frame minibuffer 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
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 w32notify w32
lcms2 multi-tty make-network-process emacs)

Memory information:
((conses 16 553323 289775)
 (symbols 48 36269 5)
 (strings 32 176312 28164)
 (string-bytes 1 5172768)
 (vectors 16 61184)
 (vector-slots 8 1564910 256562)
 (floats 8 924 1868)
 (intervals 56 4225 2135)
 (buffers 1000 124))

-- 
Juan José García Ripoll

Quantum Information and Foundations Group
Institute of Fundamental Physics IFF-CSIC
Calle Serrano 113b, Madrid 28006 Spain
http://quinfog.hbar.es - http://juanjose.garciaripoll.com