// When run with -race, this causes the condition in https://go.dev/issue/65123 often
	// enough to detect reliably.
	for _ = range rw.Header() {
	}
}

func Test1xxResponses(t *testing.T) {
	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		h := w.Header()
		h.Add("Link", "</style.css>; rel=preload; as=style")