Ensure that primary key value is valid when using Custom primary keys in Ecto.Repo.Backend.insert/4
Don't call Ecto.Model.put_primary_key/2 unless pk_field is valid
Integration Test for explicitly assigned non-default primary keys using Postgres adapter
Merge pull request #220 from TanYewWei/20140512-custom-primary-key

Ensure that primary key value is valid when using Custom primary keys in Ecto.Repo.Backend.insert/4