bug#45946: 28.0.50; hl-line-sticky-flag not working

[Gabriel do Nascimento Ribeiro]

1) emacs -q      # start emacs
2) C-x 3         # split window right
3) C-x <left>    # go to previous buffer (*scratch*)
4) eval the following expression:
     (setq-default hl-line-sticky-flag nil)
5) M-x hl-line-mode    # enable hl-line-mode in current buffer
6) C-x o               # other window (*GNU Emacs*)
7) M-x hl-line-mode    # enable hl-line-mode in current buffer
8) C-x o multiple times to change the selected window

Expected result: the line is highlighted only in selected window
Actual result: sometimes the line in non-selected window is not unhighlighted

---

In GNU Emacs 28.0.50 (build 39, x86_64-pc-linux-gnu, GTK+ Version 3.24.23, 
cairo version 1.16.0)
 of 2021-01-16 built on precision5540
Repository revision: 25e1b732947bcba51e457a7168eba6608fb666c0
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12009000
System Description: Ubuntu 20.10

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG
LCMS2 LIBSELINUX LIBXML2 MODULES NOTIFY INOTIFY PDUMPER PNG RSVG SOUND
THREADS TIFF TOOLKIT_SCROLL_BARS X11 XDBE XIM XPM GTK3 ZLIB

Important settings:
  value of $LC_CTYPE: pt_BR.UTF-8
  value of $LC_MONETARY: pt_BR.UTF-8
  value of $LC_NUMERIC: pt_BR.UTF-8
  value of $LC_TIME: pt_BR.UTF-8
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  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
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort emacsbug mail-extr cursor-sensor nndraft nnmh utf-7 gnutls
network-stream nsm nnnil gnus-agent gnus-srvr gnus-score score-mode
nnvirtual gnus-msg nntp gnus-cache smtpmail sendmail misearch
multi-isearch rx org-element avl-tree generator ol-eww eww xdg url-queue
mm-url ol-rmail ol-mhe ol-irc ol-info ol-gnus nnselect gnus-search
eieio-opt speedbar ezimage dframe gnus-art mm-uu mml2015 mm-view
mml-smime smime dig gnus-sum shr kinsoku svg dom browse-url url
url-proxy url-privacy url-expand url-methods url-history url-cookie
url-domsuf url-util url-parse url-vars mailcap gnus-group gnus-undo
gnus-start gnus-dbus dbus xml gnus-cloud nnimap nnmail mail-source utf7
netrc nnoo parse-time gnus-spec gnus-int gnus-range message rmc puny
rfc822 mml mml-sec epa derived epg epg-config mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader gnus-win
gnus nnheader gnus-util rmail rmail-loaddefs auth-source cl-seq eieio
eieio-core cl-macs eieio-loaddefs password-cache json map rfc2047
rfc2045 ietf-drums mail-utils mm-util mail-prsvr wid-edit ol-docview
doc-view image-mode exif dired dired-loaddefs ol-bibtex bibtex iso8601
ol-bbdb ol-w3m org ob ob-tangle ob-ref ob-lob ob-table ob-exp org-macro
org-footnote org-src ob-comint org-pcomplete pcomplete comint ansi-color
ring org-list org-faces org-entities noutline outline org-version
ob-emacs-lisp ob-core ob-eval org-table ol org-keys org-compat advice
org-macs org-loaddefs format-spec cal-menu calendar cal-loaddefs vc-git
diff-mode easy-mmode conf-mode dabbrev jka-compr find-func cl-print
time-date subr-x cl-extra shortdoc text-property-search seq byte-opt gv
bytecomp byte-compile cconv hl-line thingatpt help-fns radix-tree
help-mode easymenu cl-loaddefs cl-lib iso-transl 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 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 button
loaddefs faces cus-face macroexp files window text-properties overlay
sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote threads dbusbind inotify lcms2
dynamic-setting system-font-setting font-render-setting cairo
move-toolbar gtk x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 216767 12349)
 (symbols 48 22643 1)
 (strings 32 76291 2945)
 (string-bytes 1 2499291)
 (vectors 16 35895)
 (vector-slots 8 445907 18792)
 (floats 8 315 136)
 (intervals 56 1217 0)
 (buffers 984 24))