Boot blocked on SSH host keys gen.

[vholer]

On Debian/Ubuntu, we generate missing SSH host keys by triggering package reconfiguration, e.g.:

if [ ! -f /etc/ssh/ssh_host_rsa_key ]; then
    DEBIAN_FRONTEND=noninteractive dpkg-reconfigure openssh-server
fi

Inside the dpkg-reconfigure, the restart of SSH is triggered. Running this from inside the existing service running early before SSH itself, this can block the one-context-local and also complete machine boot.

Observed on Ubuntu 21.04.

[vholer]

Fixed by #224