zoneinfo: Update /etc/localtime when upgrading timezones.
* Add tzsetup(8) to the bootstrap-tools.
* Install the backward file to retain obsolete timezones as links
for backward compatibility. Remove all these timezones from
Makefile_upgrade.inc again. Also extend mtree/BSD.usr.dist for
this and remove the old 'dragonfly' file (which was only for UTC).
* After installing new timezones, run tzsetup -r to upgrade the user's
chosen timezone. Allow this to fail for quickworlders. It will start
working after the next full buildworld.
Taken-from: FreeBSD (with modifications)
projects / dragonfly.git / commit