generate_email_supportuser was not creating user which can
be used by messaging system. core_user::get_support_user()
should be used to get support_user record.
internal means "uses password hash for user authentication", there is a new is_synchronised_with_external() method that indicates if moodle should automatically sync user info with external system after login; I have also improved the default for prevent_local_passwords() which is now defaulting to !is_internal()