OpenBSD lets you use custom file sets and shell scripts during binary upgrades. If you have a lot of machines to upgrade, run these to ensure that your systems are as identical after the upgrade as they were before. I highly recommend automating known changes during an upgrade.
The siteXX.tgz file works for upgrades exactly as for installations. Put the files you want on this system in siteXX.tgz, and the install program should copy those files to the system as it installs the upgraded files. Rather than
install.site, however, the upgrade software looks for the script
upgrade.site. Any install.site file is ignored during an upgrade, so you can use the same siteXX.tgz for upgrades and for new installations.
I find the