Why is my head bone disappearing after importing blender character to unity

So I made a model, rigged it and animated it. Now I wan't to import it into Unity and use it. I am able to import it, but when I import it and change the animation rig options to humanoid it can't configure the character. So I need to configure it myself... But when I press configure the head bone is gone! In blender I can clearly see the headbone is there but importing it into unity makes it disappear. I need some help because I can't do it on my own. If you need the .blend file I uploaded it to http://pasteall.org/blend/40910 You can try to import the file yourself and try to configure the rig humanoid options to see what I mean, or you can press Z in the blend file to see the bones. Thanks!