title: accepts_nested_attributes_for with belongs_to polymorphic
body: <p>I would like set up a polymorphic relation with <code>accepts_nested_attributes_for</code>. Here is the code:</p>
  
  <pre><code>class Contact &lt;ActiveRecord::Base
    has_many :jobs, :as=&gt;:client
  end
  
  class Job &lt;ActiveRecord::Base
    belongs_to :client, :polymorphic=&gt;:true
    accepts_nested_attributes_for :client
  end
  </code></pre>
  
  <p>When I try to access <code>Job.create(..., :client_attributes=&gt;{...}</code> gives me <code>NameError: uninitialized constant Job::Client</code></p>