`USE DB` check privileges using the DBIsVisible function, that function should
take role into consideration

	CREATE DATABASE app_db
	CREATE ROLE 'app_developer'
	GRANT ALL ON app_db.* TO 'app_developer
	CREATE USER 'dev'@'localhost
	GRANT 'app_developer' TO 'dev'@'localhost'
	SET DEFAULT ROLE 'app_developer' TO 'dev'@'localhost'

login as 'dev'@'localhost'
Before:
  mysql> use app_db
  ERROR 1044 (42000): Access denied for user 'dev'@'localhost' to database 'app_db'

After:
  mysql> use app_db;
  Database changed