Fix the case when a remote user copy a file with sudo priviledge

In my case, the env var SUDO_USER exists but do the action with uid=0 => move.
The problem happen when the src file is readonly for the root because it was copied by the remote_user.

In any case the clean up will happen at the end. So it doesn't matter if we let the src file.

Note : the unit test "test_copy" doesn't pass in selinux neither before and after this patch. (pass if not selinux).