I moved a SpriteKit project from Xcode64 to Xcode7, ran it in a iOS9 simulator and the screen content is shifted. (It is not shifted when running in iOS8 simulator.)
With the release of Xcode 7.2 the issue can be fixed by opening each scene file (.sks) and saving it once. The yellow frame and the content (see the screenshots in my question) are again aligned nicely to another when zooming in and out.