check terms ancestry on post save (wordpress)

/* IF A CHILD TERM IS SET, ALSO SET PARENT TERM (TAXONOMY NAME 'SEKTION' )*/
function check_terms_ancestry($post_id) {
    if(!wp_is_post_revision($post_id)) {
        $terms_parents = array();
        $terms = wp_get_post_terms($post_id, 'sektion');
        foreach ($terms as $term) {
            array_push($terms_parents, $term->parent);
        }
        if($terms_parents) {
            array_unique($terms_parents);
            wp_set_post_terms($post_id, $terms_parents, 'sektion', TRUE);
        }
    }
}
add_action("save_post", "check_terms_ancestry", 10, 2);