Once again I am unable to do an update.
First, I tried the standalone updater. The package installer gave me an error with a giant yellow caution sign. It said, "The installation failed. Could not prepare Security Update 2018-001 for installation. Try installing from a different copy of the item or contact the manufacturer for assistance." I called Apple and they were very sorry this happened. Tim's going to get back to me later today with a fix. Actually, to be accurate, Apple doesn't care about me. I made up the part about calling Apple. The error message is totally, 100% real, though.
In past updates, the App Store update wouldn't work, but the standalone updater would work or vice versa. I figured, "OK, this is one of those times when the standalone updater doesn't work but (fingers crossed) the App Store update will work."
So I tried the App Store update. I got a little bit further with this. After it finished downloading, there was a message about restarting. So far so good. Pressed restart. The screen turned black and there was a progress bar. After a bit it (the progress bar) said "Restarting." The progress bar went away and there was a momentary gray spinner. Then the first reboot. Alas, in Clover, I didn't get the "Install Mac OS from ..." boot option.