Comment 12 for bug 295080

Steve, let me quote from Celso's answer:

I don't think we have done that before, but as I and Colin said on
#soyuz, custom uploads we can only be copied using `cp`, it's a pure
disk operation.

Just be sure `cron.publisher-ftpmaster` is not running (stop it if
necessary, otherwise your changes to /dists will be overwritten), and
the copy the dists/intrepid-proposed/<path to ddtp> to
dists/intrepid-updates/<path to ddtp>.

There might be necessary to create <path to ddtp> in the destination dists.