get_course_users now calls get_site_users if the course is a site.

get_course_users now calls get_site_users if the course is a site.

There is something wrong with this SQL still though ... it mostly works
but I'm still getting wierd behaviour with small numbers of users.

Need some help here ...  for example just look at get_site_users()
on your test site.

It's supposed to return a list of users who are admins, creators,
teachers or students