freebsd-update(8) upgrade, install, install: files not found

From: Graham Perrin <grahamperrin_at_gmail.com>
Date: Sat, 02 Apr 2022 14:28:33 UTC
With the second run of /usr/sbin/freebsd-update install (after 
restarting the system), is it sometimes normal for freebsd-update to 
report files not found?

Screenshot: <https://i.imgur.com/BL8Mk4r.png> ‒ the tail end of an 
upgrade from 13.0-RELEASE-p8 (userland p10) to 13.1-RC1.

The four files not found, including /etc/rc.d/zfskeys (more 
specifically: ///var/db/etcupdate/current/etc/rc.d/zfskeys) were files 
that did not exist prior to the upgrade.