No, rsync is not available as a direct Jenkins plugin (we could run it manually of course from a command-line step, but that becomes more work to deploy across different slaves). However I've found a different SFTP plugin (does SSH as well as SCP) which can execute remote commands after copying artefacts - which should do the job nicely. Just testing that out now!
Right, the alternate plugin does the correct thing - the copy in releases/ should always be a complete build now. I've also moved past versions to 'previous' subdir.
These builds seem sane to me, so I think some wider testing is warranted!