/* Insert with callback on existing. */
trbt_insert32_callback(rb, 0, insert_callback, data2);
ok1(strcmp(trbt_lookup32(rb, 0), "insert_callback") == 0);
/* Insert with callback on existing. */
trbt_insert32_callback(rb, 0, insert_callback, data2);
ok1(strcmp(trbt_lookup32(rb, 0), "insert_callback") == 0);