pt-osc --null-to-not-null description is wrong

mysql> CREATE TABLE actor (
    ->   actor_id SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT,
    ->   first_name VARCHAR(45) NOT NULL,
    ->   last_name VARCHAR(45) NOT NULL,
    ->   ola_breach_status int(11),
    ->   PRIMARY KEY  (actor_id),
    ->   KEY idx_actor_last_name (last_name)
    -> )ENGINE=InnoDB DEFAULT CHARSET=utf8;
Query OK, 0 rows affected (0.01 sec)mysql>
mysql> INSERT INTO actor (first_name,last_name) VALUES ('PENELOPE','GUINESS');
Query OK, 1 row affected (0.00 sec)mysql> INSERT INTO actor (first_name,last_name) VALUES ('PENELOPE','GUINESS');
Query OK, 1 row affected (0.00 sec)mysql> INSERT INTO actor (first_name,last_name) VALUES ('PENELOPE','GUINESS');
Query OK, 1 row affected (0.00 sec)mysql> select * from actor;
+----------+------------+-----------+-------------------+
| actor_id | first_name | last_name | ola_breach_status |
+----------+------------+-----------+-------------------+
|        1 | PENELOPE   | GUINESS   |              NULL |
|        2 | PENELOPE   | GUINESS   |              NULL |
|        3 | PENELOPE   | GUINESS   |              NULL |
+----------+------------+-----------+-------------------+
3 rows in set (0.00 sec)

[root@yunus-uyanik-default ~]# pt-online-schema-change h=localhost,D=test,t=actor --alter "modify column ola_breach_status int(11) unsigned NOT NULL DEFAULT 123" --null-to-not-null --execute
mysql> select * from test.actor;
+----------+------------+-----------+-------------------+
| actor_id | first_name | last_name | ola_breach_status |
+----------+------------+-----------+-------------------+
|        1 | PENELOPE   | GUINESS   |                 0 |
|        2 | PENELOPE   | GUINESS   |                 0 |
|        3 | PENELOPE   | GUINESS   |                 0 |
+----------+------------+-----------+-------------------+
3 rows in set (0.00 sec)