stroke color not transparent on iOS 7

With dark background I can see that outer stroke color is not transparent:
![sc](https://cloud.githubusercontent.com/assets/3737798/2865208/e3381044-d219-11e3-9abf-3c4eaefc2a96.PNG)

example project: https://github.com/mkutgt72/PopoverProblem.git

btw how to change outerStrokeColor for popover instance (see example for more details)?