This command attempted to create sandboxed containers for running
systemd services that exist on the host. This code has proved very
fragile, however, since it needs heuristics to figure out which dirs
need to be made private in the container vs shared with the host. Even
a relatively simple "httpd.service" sandbox no longer works with
current Fedora.

Users wanting to sandbox services are better served by using systemd's
native container functionality, or using Docker container images. The
virt-sandbox-image tool can even run Docker/virt-builder images directly.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>