bug#46689: 28.0.50; Behavior changed in latest Gcc Emacs

[Violin Learner]

In the latest Gcc Emacs, selecting some text within Emacs will change the result of (current-kill 0). However, the old behavior was that only selecting text in the external programs other than Emacs would change what (current-kill 0) returns.

Reproduce steps:

1. Evaluate (setq select-enable-primary t)
2. Evaluate (current-kill 0), and note the result
3. Hit C-<SPC>, move the cursor to select some text
4. Evaluate (current-kill 0) again, and the result will be the text just been selected in step 3. However, the result used to be the same as in step 2.


In GNU Emacs 28.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.25, cairo version 1.17.4)
 of 2021-02-18 built on york-asus
Repository revision: f92bb788a073c6b3ca7f188e0edea714598193fd
Repository branch: makepkg
Windowing system distributor 'The X.Org Foundation', version 11.0.12010000
System Description: Arch Linux

Configured using:
 'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --mandir=/usr/share/man --with-gameuser=:games
 --with-sound=alsa --with-modules --without-gconf --without-gsettings
 --with-nativecomp --with-x-toolkit=gtk3 --without-xaw3d
 --without-m17n-flt --with-cairo --without-compress-install
 'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fno-plt -g
 -fuse-ld=gold' CPPFLAGS=-D_FORTIFY_SOURCE=2
 LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now'

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

Important settings:
  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 mail-extr emacsbug comp comp-cstr warnings rx message rmc
puny dired dired-loaddefs rfc822 mml mml-sec epa derived epg epg-config
gnus-util rmail rmail-loaddefs auth-source cl-seq eieio eieio-core
cl-macs eieio-loaddefs password-cache json map time-date subr-x
mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils
mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr
mail-utils debug backtrace find-func shortdoc text-property-search pp
cl-extra seq byte-opt gv bytecomp byte-compile cconv cl-print thingatpt
help-fns radix-tree misearch multi-isearch tutorial 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 pcase 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
font-render-setting cairo move-toolbar gtk x-toolkit x multi-tty
make-network-process nativecomp emacs)

Memory information:
((conses 16 102488 9169)
 (symbols 48 8711 1)
 (strings 32 26150 2215)
 (string-bytes 1 939191)
 (vectors 16 16803)
 (vector-slots 8 341263 16097)
 (floats 8 77 114)
 (intervals 56 324 0)
 (buffers 992 15))