title: Why does persisted? return true after ActiveRecord::Rollback?
body: <p>Example:</p>
  
  <pre><code>BillingProfile.transaction do
    if @billing_profile.save
      unless SomeService.do_something # returns false and rollback occurs
        raise ActiveRecord::Rollback
      end
    end
  end
  
  @billing_profile.persisted? # Still return true, despite rollback
  @billing_profile.id # Is set, despite rollback
  </code></pre>
  
  <p>Why wouldn't the state of @billing_profile reflect that the record was rolled back?</p>
  
  <p>This is a problem since the record cannot be created after it has been rolled back.</p>