I have copied and pasted some source code from one old xcode-project to another new project.
Included in the copied code where some @IB
My current conclusion is that xcode (7.3.1) contains a bug (or shortcoming).
If I terminate xcode and then open my new project then everything looks good.
If I then open the old project, and also open the old storyboard within that project, then the false bullet links becomes visible in my new project.
My guess is that xcode scans through all storyboards, that are currently opened in any project, to find a link between an outlet name such as "buyButton" and a storyboard.