One spec was only passing due to a bug. The setup wasn't complete and
despite the variant being unavailable in the order cycle it was reported
as being available. The order cycle has now been set up correctly.
Another spec was added to cover an edge case lead to a bug before this
pull request. When all subscription items where unavailable, all were
marked as available.
At `CapQuantity`'s instantiation time the proxy's order is not yet
initialized, and so `CapQuantity` was checking against nil all the time.
This went unnoticed because the job's specs were not integration-level
tests and were stubbing way too many things.
