title: UINavigationItem's title disappears when view controller is pushed
body: <p>I am having an issue with my view controller's navigation item's title. Indeed, I am setting it in the <code>viewDidLoad</code> method like this :</p>
  
  <pre><code>self.navigationItem.title = "Title"
  </code></pre>
  
  <p>The problem is that when I push this view controller from another on to the navigation stack, I see the title while the transition but as soon as the transition ends, it disappears... I checked in the debugger, the title is still set... I tried with the titleView property either with no success...
  By the way, the problem only show up on iPhone 5 with iOs &lt; 9...</p>