failing test for polymorphic relationship being set up correctly

The example is a bit contrived with naming, since I was trying to use existing models, but the idea is that a post can belong to an email or a telephone, both of which extend `contact`. You should be able to add any polymorphic model that extends contact and set it as contact when creating a post, but you get the following error: `Assertion Failed: You cannot add 'email' records to this relationship (only 'contact' allowed)`

A contact is clearly an email.