handler_savepoint_rollback should be DERIVE type

mysql> show global status like 'Handler_savepoint%';
+----------------------------+-------+
| Variable_name | Value |
+----------------------------+-------+
| Handler_savepoint | 0 |
| Handler_savepoint_rollback | 0 |
+----------------------------+-------+
2 rows in set (0.00 sec)

mysql> begin;
Query OK, 0 rows affected (0.00 sec)

mysql> insert into t1 values (1);
Query OK, 1 row affected (0.01 sec)

mysql> savepoint aaa;
Query OK, 0 rows affected (0.00 sec)

mysql> insert into t1 values (1);
Query OK, 1 row affected (0.00 sec)

mysql> rollback to savepoint aaa;
Query OK, 0 rows affected (0.00 sec)

mysql> show global status like 'Handler_savepoint%';
+----------------------------+-------+
| Variable_name | Value |
+----------------------------+-------+
| Handler_savepoint | 1 |
| Handler_savepoint_rollback | 1 |
+----------------------------+-------+
2 rows in set (0.00 sec)

Yeah, Handler_savepoint_rollback is constantly increasing counter and should be DERIVE.