Yeah, it happened again...
Right after I updated, everything was dead.
However, using Marek's fix worked again! (Yay Marek!!)
This time the updated packages were:
libblkid
libmount
libuuid
util-linux
Also, FWIW, this time Tor was not exempt.
(If you're not already familiar with Marek's fix, it's running "sudo sh qubes_setup_dnat_to_ns" in your netvm.)