This is a Devuan-native package, so nobody can blame Debian here.
This bug is trivial to reproduce, was filed over 7 months ago, and has seen absolutely zero action.
This has a very real potential to leave people with an unbootable system, as _intentional_ misbehaviour of 'systemd-detect-virt' causes /etc/kernel/postinst.d/zz-update-grub to skip updating the bootloader.

/etc/kernel/postinst.d/zz-update-grub:

if type systemd-detect-virt >/dev/null 2>&1 &&
   systemd-detect-virt --quiet --container; then
        exit 0
fi

/usr/sbin/systemctl:

case "${0}" in
   *hostnamectl|*systemd-detect-virt) exit 0 ;; # always just short-circuit
esac

Was this package added to Devuan as a trap?
Did anyone test it?
Where has the maintainer been for the last 7 months?
What the hell is going on?