From: http://dev.mysql.com/doc/refman/5.0/en/drop-database.html
...when a database is dropped, user privileges on the database are not automatically d
REVOKE ALL PRIVILEGES FROM '%'@'%';
The above could be dangerous as i suppose it will delete all the privileges from all the users including root
Modify it to:
REVOKE ALL PRIVILEGES FROM 'user'@'localhost';
or
REVOKE ALL PRIVILEGES FROM 'user'@'%';
before execute