title: Deinit never called
body: <p>I'm creating a ViewController object an pushing it to a navigation controller.
  When the object is being popped from the stack - it is not being release and Deinit is not being called. What can be the reason for that?</p>
  
  <p>Here's the code that pushes:</p>
  
  <pre><code>self.navigationController?.pushViewController(CustomViewController(), animated: true)
  </code></pre>
  
  <p>And here's the code that pops:</p>
  
  <pre><code> self.navigationController?.popViewControllerAnimated(true)
  </code></pre>