message: nydus-image: avoid copy child node when apply node to tree
  Avoid copy child node when apply node to tree.
diff: @@ -132,10 +132,7 @@ impl Tree {
  if depth == target_paths_len - 1 {
  let mut node = target.clone();
  node.overlay = Overlay::UpperModification;
  - *child = Tree {
  - node,
  - children: child.children.clone(),
  - };
  + child.node = node;
  return Ok(true);
  }
  if child.node.is_dir() {
  