You can "upgrade" existing FreeBSD system, by selecting
	"Upgrade" option of sysinstall. However, sysinstall does not
	recover some /etc files such as /etc/sendmail.cf, etc.

	After you have finished upgrading FreeBSD, you have lost your
	configulation files. It may causes some serious results.

	Some /etc/rc.firewall users also get stucked. Yes, rc.firewall
	keeps during the upgrade but it causes the bomb; there is
	no source_rc_confs() to suck the config variables.

Fix: 

All need-to-restore-after-installation /etc files should be
	listed in src/release/sysinstall/installUpgrade.c.

	All FreeBSD committers who creates some files in /etc should
	check "etc_files" variable. If your file is missing, it should
	be added if you want the user to keep modified file during the
	system upgrade (with approvals of sysinstall maintainer).

	This is a list of new candidates of etc_files, but not limited to:
		apmd.conf, dhclient.conf, hosts.allow, isdn/,
		protocols, pccard.conf, pccard_ether, periodic.conf,
		phones, pim6dd.conf, pim6sd.conf, rpc, security, ssh/,
		ssl/, usbd.conf.

	Some rc.* files are maybe also the canididates. However, it's
	too hard to resolv rc.firewall problem described above. It
	should be keeped, however it causes troubles if sysinstall keeps.

	Should we do /etc upgrading procedures with mergemaster(8)?
How-To-Repeat: 
	Shutdown your FreeBSD box, boot with floppy. When sysinstall
	comes up, select "Upgrade" to upgrade your system, and reboot.