After the upgrade, I found that I still had the debian version of dbus (plus libdbus and dbus-x11) installed,
despite devuan replacements being available. (IIRC this was manifesting as problems with xserver
trying to access a system login service or something.)

The installed one was 1.10.24 (I think) which the system presumably decided to preserve rather than
using the devuan 1.10.22 versions. (I see that debian stretch now offers 1.10.26 - it had probably been
a while since I had updated stretch prior to the migration.)

Forcibly installing the 3 packages at the devuan revision numbers downgraded them.

I see that bug #95 was a similar problem a while back.  Perhaps the newer version is already
in a queue to get added to ascii.