Correct faulty logic when dealing with autocomplete_users_for_site_admins, and...

Correct faulty logic when dealing with autocomplete_users_for_site_admins, and break logic into multiple lines. See #19810.


git-svn-id: https://core.svn.wordpress.org/trunk@19934 1a063a9b-81f0-0310-95a4-ce76da25c4cd