title: Go listen on port which is already in use not returning error
body: <p>I already have a webserver which is listening on port 80 (written in node.js). When I run another webserver that also listens on port 80 (written in Go), the Go webserver doesn't raise an error. </p>
  
  <p>How can this occur. </p>
  
  <p>My OS is windows and go version go1.2.2.</p>