title: UINavigatorController popViewController:animated shows strange behaviour in iOS 5.1 but not in iOS 6
body: <p>I found out some strange behaviour that I can't explain in my iOS App.</p>
  
  <p>I'm using a standard UINavigationController that is embedded in a UITabBarController Subclass. </p>
  
  <p>When I push a ViewController on the NavigationController the animation is just fine. But when a ViewController is popped in Landscape the pop animation happens from the top of the screen to the lower end in contrast to the right to left standard behaviour that is expected. </p>
  
  <p>Even more strange that the TabBar is included in the animated transition, which is also not the case in Portrait mode. </p>
  
  <p>This happens only on iOS 5 devices, and at the moment I just don't have a clue why this happens.</p>