使用Appengine标准时，重定向不会从POST切换到GET

Like the title says, a curl request to the following server written for appengine with GO doesn't switch from POST to GET despite the redirection :

func init() {
    http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        switch r.Method {
        case "GET":
            fmt.Fprintf(w, "INDEX")
        case "POST":
            fmt.Print("redirecting...")
            http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
        default:
            http.NotFound(w, r)
        }
    })
}

Instead, I get an infinite redirection loop, no matter what status code I try (302,303,...)

My routing in app.yaml for the record :

- url: /.*
  script: _go_app  

And the curl command used locally :

curl "http://localhost:8080" -X POST -L

How do I fix this ? thanks .

EDIT: The behavior remained unchanged with 302

http.Redirect(w, r, "/", http.StatusFound)

It is still stuck in a redirection loop