bug#56482: 29.0.50; shr displays <![if !supportLists]>...<![endif]> literally instead of dropping the tags

[Justus-dev]

In gnus with the default shr html renderer, incoming HTML mails
containing <![if !supportLists]>...<![endif]> tags will show these
literally. Instead, since (as I understand) shr is not designed to
handle the surrounding CSS magic and does not in fact support "Lists",
it should simply eliminate the <![if !supportLists]> and <![endif]> tags
and display just the enclosed text.

This may in fact be a libxml2 limitation with no clean solution in shr,
but I don't at this point understand libxml2 nor shr well enough to
tell.


In GNU Emacs 29.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.34, cairo 
version 1.17.6)
 of 2022-07-06 built on piater
Repository revision: 15404818503e0d3df7a8c56af13e4123bd231989
Repository branch: master
System Description: Arch Linux

Configured using:
 'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --mandir=/usr/share/man --with-gameuser=:games
 --with-modules --without-libotf --without-m17n-flt --without-gconf
 --with-native-compilation --with-xinput2 --with-pgtk --without-xaw3d
 --with-sound=no --without-gpm --without-compress-install
 '--program-transform-name=s/\([ec]tags\)/\1.emacs/'
 'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fno-plt -fexceptions
 -Wp,-D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security
 -fstack-clash-protection -fcf-protection -flto=auto'
 'LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now -flto=auto''

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG JSON
LCMS2 LIBSYSTEMD LIBXML2 MODULES NATIVE_COMP NOTIFY INOTIFY PDUMPER PGTK
PNG RSVG SECCOMP SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS WEBP XIM GTK3
ZLIB

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

Major mode: Article

Minor modes in effect:
  global-git-commit-mode: t
  magit-auto-revert-mode: t
  override-global-mode: t
  shell-dirtrack-mode: t
  pdfgrep-mode: t
  pdf-occur-global-minor-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  context-menu-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  buffer-read-only: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
/home/piater/.config/emacs/elpa/transient-20220527.2213/transient hides 
/usr/share/emacs/29.0.50/lisp/transient

Features:
(shadow emacsbug finder-inf html2text gnus-html cl-print ps-mule
ps-print ps-print-loaddefs ps-def lpr calc-incom calc-alg calc-ext
calc-menu calc calc-loaddefs rect calc-macs nndoc ein-ipynb-mode js
ein-process ein-jupyter ein-dev ein-notebook ein-python-send
ein-traceback ein-pytools ein-pager ein-completer ein-notification
ein-scratchsheet ein-worksheet poly-ein quail ein-kill-ring ein-cell
ein-shared-output ein-output-area ein-kernelinfo ein-kernel ein-ipdb
ein-events ein-websocket websocket bindat ein-file ein-node
ein-notebooklist shortdoc ido ein-contents-api ein-query ein-log
ein-classes ein-core request anaphora ein-utils deferred cc-mode
cc-fonts cc-guess cc-menus cc-cmds cc-styles cc-align cc-engine cc-vars
cc-defs ein pcmpl-unix pcmpl-gnu locate magit-patch magit-subtree
magit-gitignore magit-ediff ediff ediff-merg ediff-mult ediff-wind
ediff-diff ediff-help ediff-init ediff-util conf-mode find-dired
latexenc poly-markdown markdown-mode mm-extern gnus-search eieio-opt
speedbar ezimage dframe org-clock vc-src vc-sccs vc-svn vc-cvs vc-rcs
log-view vc bug-reference magit-extras rng-xsd xsd-regexp rng-cmpct
rng-nxml rng-valid nxml-mode nxml-outln nxml-rap sgml-mode
magit-bookmark magit-submodule magit-obsolete magit-blame magit-stash
magit-reflog magit-bisect magit-push magit-pull magit-fetch magit-clone
magit-remote magit-commit magit-sequence magit-notes magit-worktree
magit-tag magit-merge magit-branch magit-reset magit-files magit-refs
magit-status magit magit-repos magit-apply magit-wip magit-log
which-func magit-diff smerge-mode diff git-commit log-edit pcvs-util
add-log magit-core magit-autorevert autorevert magit-margin
magit-transient magit-process with-editor magit-mode magit-git
magit-base crm python tramp-cmds vc-hg vc-git diff-mode vc-bzr
vc-dispatcher tramp-sh tramp-archive tramp-gvfs tramp-cache zeroconf
view woman man arc-mode archive-mode pdf-sync pdf-annot facemenu
pdf-outline pdf-links pdf-history tex-mode diary-lib diary-loaddefs
cal-iso eudc-capf eudc cus-start eudc-vars display-line-numbers
ement-taxy taxy-magit-section magit-section dash compat-27 compat-26
taxy svg-lib ement-room-list cal-move sh-script smie executable timezone
dabbrev tabify poly-org polymode poly-lock polymode-base polymode-weave
polymode-export polymode-compat polymode-methods polymode-core
polymode-classes eieio-custom eieio-base ffap org-super-links
org-capture dired-aux org-indent ol-eww eww xdg url-queue thingatpt
ol-rmail ol-mhe ol-irc ol-info ol-gnus nnselect ol-docview ol-bibtex
ol-bbdb ol-w3m ol-doi org-link-doi mailalias smtpmail flow-fill
shr-color gnus-topic misearch multi-isearch gnus-draft mule-util smiley
gnus-cite matlab matlab-scan matlab-syntax matlab-compat pulse mail-extr
textsec uni-scripts idna-mapping ucs-normalize uni-confusable
textsec-check gnus-async gnus-bcklg sort gnus-ml disp-table mm-archive
url-http url-gw url-cache url-auth qp utf-7 network-stream nsm imap
rfc2104 epa-file nnrss nndraft nnmh nnfolder nnmaildir gnus-agent
gnus-srvr gnus-score score-mode nnvirtual gnus-msg gnus-art mm-uu
mml2015 mm-view mml-smime smime gnutls dig nntp gnus-cache gnus-sum
gnus-group gnus-undo mm-url gnus-start gnus-dbus gnus-cloud nnimap
nnmail mail-source utf7 netrc nnoo gnus-spec gnus-int gnus-range message
sendmail yank-media rfc822 mml mml-sec epa derived epg rfc6068
epg-config mailabbrev gmm-utils mailheader gnus-win gnus nnheader
gnus-util mail-utils range gnus-dired use-package-bind-key bind-key
ement ement-notify notifications dbus ement-room transient comp
comp-cstr edmacro kmacro compat compat-macs face-remap shr pixel-fill
kinsoku url-file url-dired puny svg dom ewoc ement-lib ement-api
ement-structs ement-macros warnings xml color dns plz quelpa-use-package
cl-extra use-package-core quelpa mm-decode mm-bodies mm-encode
mail-parse rfc2231 rfc2047 rfc2045 mm-util ietf-drums mail-prsvr
lisp-mnt help-fns radix-tree help-mode ox-odt rng-loc rng-uri rng-parse
rng-match rng-dt rng-util rng-pttrn nxml-parse nxml-ns nxml-enc xmltok
nxml-util ox-latex ox-icalendar ox-html table ox-ascii ox-publish ox
org-element avl-tree generator org-agenda org-id org-refile yaml-mode
native-complete shell-here tramp tramp-loaddefs trampver
tramp-integration files-x tramp-compat shell parse-time ls-lisp
org-recoll doc-view filenotify org ob ob-tangle ob-ref ob-lob ob-table
ob-exp org-macro org-footnote org-src ob-comint org-pcomplete pcomplete
org-list org-faces org-entities noutline outline easy-mmode org-version
ob-emacs-lisp ob-core ob-eval org-table oc-basic bibtex iso8601
time-date ol rx org-keys oc org-compat org-macs org-loaddefs cal-menu
calendar cal-loaddefs pdfgrep grep pdf-occur ibuf-ext ibuffer
ibuffer-loaddefs tablist advice tablist-filter semantic/wisent/comp
semantic/wisent semantic/wisent/wisent semantic/util-modes semantic/util
semantic semantic/tag semantic/lex semantic/fw mode-local find-func
cedet pdf-isearch let-alist pdf-misc imenu pdf-tools compile comint
ansi-color ring cus-edit cus-load wid-edit pdf-view bookmark
text-property-search pp jka-compr pdf-cache pdf-info tq pdf-util
format-spec pdf-macs image-mode dired dired-loaddefs exif server
deadgrep-autoloads ein-autoloads ement-autoloads ess-autoloads
datetime-autoloads magit-autoloads git-commit-autoloads
pdf-tools-autoloads markdown-mode-autoloads rnc-mode-autoloads
rust-mode-autoloads magit-section-autoloads info compat-autoloads
request-autoloads package browse-url url url-proxy url-privacy
url-expand url-methods url-history url-cookie generate-lisp-file
url-domsuf url-util mailcap url-handlers url-parse auth-source cl-seq
eieio eieio-core cl-macs eieio-loaddefs password-cache json subr-x map
byte-opt gv bytecomp byte-compile cconv url-vars cl-loaddefs cl-lib rmc
iso-transl tooltip eldoc paren electric uniquify ediff-hook vc-hooks
lisp-float-type elisp-mode mwheel term/pgtk-win pgtk-win term/common-win
pgtk-dnd tool-bar dnd fontset image regexp-opt fringe tabulated-list
replace newcomment text-mode lisp-mode prog-mode register page tab-bar
menu-bar rfn-eshadow isearch easymenu timer select scroll-bar mouse
jit-lock font-lock syntax font-core term/tty-colors frame minibuffer
nadvice seq simple cl-generic indonesian philippine 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 emoji-zwj charscript charprop
case-table epa-hook jka-cmpr-hook help abbrev obarray oclosure
cl-preloaded button loaddefs faces cus-face macroexp files window
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget keymap hashtable-print-readable backquote threads dbusbind
inotify dynamic-setting system-font-setting font-render-setting cairo
gtk pgtk lcms2 multi-tty make-network-process native-compile emacs)

Memory information:
((conses 16 5882393 730120)
 (symbols 48 77801 70)
 (strings 32 1594098 80708)
 (string-bytes 1 97327779)
 (vectors 16 569961)
 (vector-slots 8 8733979 876067)
 (floats 8 3658 3665)
 (intervals 56 373170 10181)
 (buffers 992 272))