After spending the time since 2016 with waiting how things will turn
out, a dying disk and certain recent Debian moves prompted me to stop
using this system (after 21 years) and migrate to the current, stable
Devuan instead[*]. Thank you for keeping the system I had been using all
these years available.

[*] This was mostly painless except that I had to update the kernel in
the installation image in order to get support for my (fairly new) Intel
NIC. In case anyone cares:

The basic procedure for this is really straight-forward: Copy the
contents of the .iso to some directory, copy the vmlinuz of your choice
over the linux file in that directory, unpack the contents of Devuan
initrd.gz into another directory[**], replace the
lib/modules/<kernel-version> directory of the result with the modules
directory of the new kernel, pack this up into a replacement initrd.gz [***]
in the first new directory, recreate a bootable ISO-image from that
[****].

Obviously, the after installation is complete, a new kernel needs to be
added to the install system, too.

Assuming the iso directory is called iso and the other ir, the commands
are (mostly from memory)

[**] cd ir; gunzip <../iso/initrd.gz | cpio -iv
[***] find . | cpio -H newc -ov | gzip -9v >../iso/initrd.gz
[****] cd ..; genisoimage  -b isolinux/isolinux.bin -c boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -r -o img iso;
       isohybrid img

The updated image will then be in the img file.