Comment 5 for bug 1889646

Hi Ian, we're using it because maas uses virsh, which connects over ssh, and we need to be able to configure ssh with keys (https://discourse.maas.io/t/ssh-setup-fix/1496) to use when connecting to a remote virsh.

ssh has the $HOME/.ssh path hardcoded, so we mount the /root dir as overlay to be able to satisfy that.