The build process is marked as successful even when the pixie vm is faulty. This led to https://github.com/pixie-lang/pixie/issues/535. <img width="1037" alt="screen shot 2018-01-11 at 11 25 47 pm" src="https://user-images.githubusercontent.com/11717556/35209424-91de0f28-ff56-11e7-8a8e-d1b675f803bb.png">
