Add remote_src option to scp_put

[cqexbesd]

If remote_src is true it indicates you wish to scp from the remote
machine. This facilitates server to server copies.

This is a duplicate of RT#105771 (I didn't think to check github first - sorry!)

[cqexbesd]

Is there any feedback for this?

[salva]

@cqexbesd, first let me apology for not having replied to this before! The truth is that I have been unable to make my mind about this feature yet.

IMO, it seems useful but does not really fit into Net::OpenSSH well enough. Also, the way it works under the hood is too convoluted and may fail in unexpected ways.

I think that for direct transfers between the two remote hosts, the right way to do that would be to just call scp with the proper arguments on the remote machine. For indirect transfers, using the local machine as a proxy (scp -3 ...) that should be done combining two Net::OpenSSH objects.

In any case, I don't think it is a good idea to reuse the names scp_put or scp_get. It is not clear what are the target and source hosts.