title: setPopoverContentSize: not working consistently on iOS 8, with xCode 6
body: <p>Recently, I've upgraded to xCode 6.  I have two iPads that I use for development; one is running iOS 7.1.2, and the other is running iOS 8.0.2.</p>
  
  <p>In my application, I'm using a <strong>UIPopoverController</strong> to display a list of items in a <strong>UITableViewController</strong>.  This has been working fine, from iOS 5 through iOS 7.  I'm creating the <strong>UIPopoverController</strong> just once, and I reuse it often throughout the app.  I want the popover to be sized just large enough to show the items in the list (anywhere from 1 to 5 items), so I'm calling <strong>setPopoverContentSize:animated:</strong> to resize the popover after I determine how large the display area should be.</p>
  
  <p>As I mentioned, this has all been working fine.  If I develop using the iPad that is running iOS 7, everything still works correctly.  But if I use the iPad running iOS 8, the very first call to <strong>setPopoverContentSize:animated</strong> sizes the popup correctly - but only on the first call.  All subsequent calls have no effect on the size of the popup.</p>
  
  <p>The released version of the app still works correctly, even if it is running on iOS 8 (it was developed and submitted to Apple using xCode 5). So this appears to be a problem related to the combination of xCode 6 and iOS 8.</p>
  
  <p>I haven't been able to figure out why only the first call to <strong>setPopoverContentSize:animated</strong> is working.  Has anyone else seen this behavior?  If so, how did you get sizing on the <strong>UIPopoverController</strong> to work correctly?</p>