This patch fixes a bug that was introduced in the latest
'run copy on object node' change as well as previous bug:
1. One bug was that we called _set_metadata_in_headers
twice: One from the PUT flow and then again from
handle_put_copy_response
2. The other bug was calling _set_metadata_in_headers
in the case of a copy where the execution is not
done in the proxy, and the object node already
takes care of the user metadata.
3. We have neglected to copy the get request headers
coming from the object node before calling the put
Change-Id: I7ea2a9f011a3050f44ee9bf7e117e758ff24c5de
f284a69b68