P_TREE_FIRST_ORPHAN
for (p = child; (p->p_treeflag & P_TREE_FIRST_ORPHAN) == 0;) {
child->p_treeflag |= P_TREE_FIRST_ORPHAN;
if ((p->p_treeflag & P_TREE_FIRST_ORPHAN) != 0) {
p1->p_treeflag |= P_TREE_FIRST_ORPHAN;
p->p_treeflag &= ~P_TREE_FIRST_ORPHAN;