Remove warning on owner re-assignment

scene/main/node.cpp

@@ -1080,6 +1080,9 @@ void Node::get_owned_by(Node *p_by,List<Node*> *p_owned) {
 
 void Node::_set_owner_nocheck(Node* p_owner) {
 
+	if (data.owner==p_owner)
+		return;
+
 	ERR_FAIL_COND(data.owner);
 	data.owner=p_owner;
 	data.owner->data.owned.push_back( this );