title: Stop Devise from clearing session
body: <p>It seems when a user logs out via standard Devise controllers, Devise destroys the entire session store, not just its own data. Is there any way to avoid this behavior? I have other irrelevant data that should be kept around.</p>
  
  <pre><code>session[:my_var] = "123"
  </code></pre>
  
  <p>Log out via devise...</p>
  
  <pre><code>puts session[:my_var]
  # =&gt; nil
  </code></pre>