How to disable go_collector metrics in prometheus/client_golang

Well the topic is rather old but in case others have to deal with it. The following code works fine with current codebase v0.9.0-pre1

// [...] imports, metric initialization ...

func main() {
  // go get rid of any additional metrics 
  // we have to expose our metrics with a custom registry
  r := prometheus.NewRegistry()
  r.MustRegister(myMetrics)
  handler := promhttp.HandlerFor(r, promhttp.HandlerOpts{})

  // [...] update metrics within a goroutine

  http.Handle("/metrics", handler)
  log.Fatal(http.ListenAndServe(":12345", nil))
}