A commit was recently introduced to attempt to surmise when a host is being registered thru a load balancer.

To do this, candlepin_proxies_controller needs to look through ::SmartProxy.all to find smart proxies matching the hostname of the server receiving the registration request.

However, if there are smart proxies assigned to locations, and those locations are not the same locations assigned to the registering user (the --username passed to subscription-manager), Rails will act as if those smart proxies don't exist.

The effect is that Katello doesn't have access to its own list of smart proxies, and so doesn't know how to correctly assign a content source.

So the host will get registered, and its "registered_through" smart proxies for REX will be correct, but content source will be incorrectly nil.