App Engine + Go version build tags

hello.go

// +build go1.3

package hello

import (
	"net/http"
	"runtime"
)

func init() {
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte(runtime.Version()))
	})
}

nope.go

// +build thistagdoesnotexist

package hello

import "net/http"

func init() {
	http.HandleFunc("/tags", func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte("wat"))
	})
}

This is deployed at http://cogent-genre-720.appspot.com/