Oof, the upgrade of this reverse proxy is just _not_ going smoothly!
Corrupted relinked #OpenBSD kernel due to /usr partition running out of space. Should have seen that coming! No problem, can still boot it from bsd.rd, so created a new larger virtual disk image, figured out an appropriate new disk layout, and reinstalled to it. Then the minimal config to get configuration management working. Configured and migrated some additional data from old image.
Phew, now it... still doesn't work. 1/N