iOS8 change pop over trait collection

I'm deploying an application on both iphone and ipad (iOS7 and iOS8).
I'm using storyboard with size classes, basically I have a base size classes Any-Any that fits iPad layout and a Compact-Regular that fits all iphone models.
SOme view controllers in the iPAd version are presented with a custom slide in/out segue, others i popovers.
While it works perfectly on iOS7 ipad (since xcode build different storyboards) on iOS8 I have the problem that what is shown in the popover picks the iphone interface.
I present it in the usual way:

    weakSelf.myPop = [[UIPopoverController alloc ] initWithContentViewController:commentVC];
 [weakSelf.myPop presentPopoverFromRect:[[(AFPostTimelineTableViewCell*)cell commentButton] frame] inView:cell permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
  weakSelf.myPop.delegate = weakSelf;

Checking the code I've seen that the presented view controller has a UITrait collection of C-R.
Is there a way to make it pick the R-R?

via Chebli Mohamed