rbackup-cmd: we can now backup a *remote* machine to a *local* server.

rbackup-cmd: we can now backup a *remote* machine to a *local* server.

The -r option to split and save allowed you to backup from a local machine
to a remote server, but that doesn't always work; sometimes the machine you
want to backup is out on the Internet, and the backup repo is safe behind a
firewall.  In that case, you can ssh *out* from the secure backup machine to
the public server, but not vice versa, and you were out of luck.  Some
people have apparently been doing this:

    ssh publicserver tar -c / | bup split -n publicserver

(ie. running tar remotely, piped to a local bup split) but that isn't
efficient, because it sends *all* the data from the remote server over the
network before deduplicating it locally.  Now you can do instead:

    bup rbackup publicserver index -vux /
    bup rbackup publicserver save -n publicserver /

And get all the usual advantages of 'bup save -r', except the server runs
locally and the client runs remotely.