just committed, will be in the next series of snapshots. so, basic installs create /etc/installurl
now, pkg_add uses it "by default" to create an installpath. pkg.conf(5) takes precedence (user defines are stronger than automatic defines): installpath = anything in pkg.conf will replace the installpath value from installurl. So, if you had an install that created /etc/installurl, and if you want pkg_add to take advantage of it, you will have to remove the installpath line you had in pkg.conf (note that you can comment it out if you're unsure whether your pkg_add supports installurl).
