When an app does a get_user() request the user gets added to the
"new user" list while its loading up.

We currently delaying loading until the "new user" list is empty,
but get_user() requests are deferred until initial loading is done,
so if a get_user() request comes in during initial load, load will
never complete.

This commit differentiates new users resulting from the initial
ListCachedUsers call and new users resulting from get_user() requests.

Only the first group inhibit the initial load from completing.