Baaah -- It would not go through on my old HP laptop, it is still hung. Hopefully it will be fixed in the next 24 hours. Meanwhile, no more DUs here.
EDIT: 3 hours later, and a full-upgrade worked correctly (2 machines). 140 packages upgraded, 13 newly installed, 1 to remove.
HOWEVER, after rebooting both machines, a few seconds after reaching the graphical target, network manager popped up a warning that although a network device was found, there was no internet found. I'm editing this post from one of the machines -- they both have the usual wired ethernet connection working correctly. These are Intel CPUs and network chips:
$ inxi -N
Network:
Device-1: Intel Ethernet I219-V driver: e1000e
So, I dunno what that is all about.