title: What causes deprecation warning: ActiveRecord::Base.raise_in_transactional_callbacks=?
body: <p>I get this message when I run my feature specs:</p>
  
  <blockquote>
    <p>DEPRECATION WARNING: ActiveRecord::Base.raise_in_transactional_callbacks= is deprecated, has no effect and will be removed without replacement.</p>
  </blockquote>
  
  <p>I am using Rails 5.0.0.rc1 and am not sure what is throwing this deprecation warning. </p>
  
  <p>I had this in my <code>application.rb</code> file.  I removed it and the deprecation warning went away:</p>
  
  <pre><code>config.active_record.raise_in_transactional_callbacks = true
  </code></pre>
  
  <p>I'd like tips on what this deprecation warning actually means and to know what triggers this deprecation warning.</p>