debootstrap from Xenial seems too old to build some images.

[nuclearsandwich]

I was getting multiple failures on my Xenial workstation when trying to build the latest round of images.

After not having much luck with debugging the issue I wound up installing the latest version of debootstrap (1.0.115) on my Archlinux workstation and they built fine there.

I haven't tried debootstrap from Ubuntu Bionic or Debian Buster since I don't have a machine running those natively and couldn't be bothered to bind Docker into a Docker container.