This thing is pointless.
Unfortunately, we cannot use Portage's `INSTALL_MASK` feature as it
doesn't work for symbolic links. Since _systemd_ installs symlinks in
`/etc/ssh` that point to files we would mask, those symlinks would point
to nothing, which would cause `sshd` to fail to start as it is unable to
open those files. Thus, we have to omit these files by excluding them
from the squashfs image.