site-users.php should use API to fetch roles

[ryan]

get_blog_option( $id, "{$blog_prefix}user_roles" )

That won't work on sites that hard code a roles array in memory. API should be used to fetch the roles. Otherwise you can end up with:

Warning: Invalid argument supplied for foreach() in /..l/wp-admin/network/site-users.php on line 149

(In [16370]) Handle sites that hard-code roles rather than storing them in the DB. Temp hack. see #15411

The "temp hack" added in [16370] existed until [21414] when it was removed

A "temp hack" we actually removed eventually? Woohoo!