title: Fails to seed: db with association
body: <p>Two models, Organization and Member, have a 1:many relationship. On basis of an <a href="https://stackoverflow.com/questions/30190890/nested-form-shouldnt-save-if-no-information-for-child-is-entered">earlier question</a>, I added to my Organization model file:</p>
  
  <pre><code>validate  :check_member
    private
    def check_member
      if members.empty?
        errors.add(:base, 'User is not present')
      end
    end
  </code></pre>
  
  <p>As a result it only creates a new organization if also a member for that organization is created. I adjusted my seeds file accordingly since I would now be unable to create an organization without a member:</p>
  
  <pre><code>Organization.create!(   name: "Fictious business",
                          address: Faker::Address.street_address,
                          city: Faker::Address.city,
                          website: Faker::Internet.url,
                          subscription: true,
                          subs_exp_date: Faker::Date.forward(365),
                          actioncode: 111,
     members_attributes: [email: "help@example.com",
                          username: "helpzzzz", 
                          password: "foobar", 
                          password_confirmation: "foobar"])
  </code></pre>
  
  <p>However it fails to seed the above, giving the error message: "ActiveRecord::RecordInvalid: Validation failed: User is not present" (referring to the error message defined in <code>def check_member</code>).</p>
  
  <p>Does anyone have an idea what I might be doing wrong?</p>
  
  <p><strong>UPDATE:</strong> It looks like it is something else that's creating the problem. In development I have no problem with seeding. However, seeding to Heroku is when the problem arises. By changing the seeds file, I have found out that when entering <code>heroku run rake db:seed</code> it is not seeding with the current, updated seeds file (while it is doing so, in development). It is using the old seeds file where the second part <code>members_attributes</code> was not included yet.</p>
  
  <p>What could be the cause of this? A problem at Heroku's side? I've also tried <code>heroku pg:reset DATABASE</code>, <code>heroku run rake db:migrate</code> and then <code>heroku run rake db:seed</code> but it was still using an old seeds file.</p>