Bug 855912 generates a different kind of receipt. This one is quite dangerous because it allows you to get a mozilla marketplace signed receipt of *any* app. The receipt has a short expiry and a different type.
We need to:
* make sure the type is enforced in our library
* make sure the expiry is enforced in our library
Document the heck out of this.
I don't think the expiry is a big deal now since the type is enforced. Expiry can fixed once bug 757226 is done.