/usr/bin/gnome-system-log-pkexec is in gnome-system-log 3.8.1-1svn1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 | #!/bin/sh
if test -r /var/log/syslog ; then
	exec /usr/bin/gnome-system-log "$@"
else
	pkexec /usr/bin/gnome-system-log "$@"
	# Run unprivileged if the user dismissed the auth dialog
	if [ $? -eq 126 ] ; then
		exec /usr/bin/gnome-system-log "$@"
	fi
fi
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