Extension:CodeReview/code bugs table

mysql> describe code_bugs;
+------------+---------+------+-----+---------+-------+
| Field      | Type    | Null | Key | Default | Extra |
+------------+---------+------+-----+---------+-------+
| cb_repo_id | int(11) | NO   | PRI | NULL    |       |
| cb_from    | int(11) | NO   | PRI | NULL    |       |
| cb_bug     | int(11) | NO   | PRI | NULL    |       |
+------------+---------+------+-----+---------+-------+