Post #1539630

@xogium Currently podman / docker don't nest within nspawn for the same reason that nspawn doesn't nest within nspawn (kernel mount shenanigans). Once we fix that you'll be able to run nspawn, docker and podman nested in nspawn (I think, there may be more issues with getting podman/docker running). If you want to run unprivileged podman/docker within nspawn they'll need to integrate with nsresourced and mountfsd (instead of using newuidmap/newgidmap like they do right now).