[t:4545], fix assert in brt_search_node

    )

{   int r = 0;

    // assert that we got a valid child_to_search

    assert(child_to_search >= 0 || child_to_search < node->n_children);

    assert(child_to_search >= 0 && child_to_search < node->n_children);

    //

    // At this point, we must have the necessary partition available to continue the search

    //