Summary: the root bug reappears when you upgrade your Mac. You need to manually reinstall Apple's security patch and reboot. There's no warning that a reboot is necessary.
Funny thing is that on the update site section steps in `To confirm that your Mac has Security Update 2017-001` confirm that I have the update, but am still vulnerable to the issue.
Do I understand correctly that setting root password is also valid workaround for the issue?