net/http: testClientHead now in http2 mode

Change-Id: I21317e3f60502759efc026cdfdb0b1d5f411cae9
Reviewed-on: https://go-review.googlesource.com/17521
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/net/http/client_test.go

@@ -83,12 +83,15 @@ func TestClient(t *testing.T) {
 	}
 }
 
-func TestClientHead(t *testing.T) {
+func TestClientHead_h1(t *testing.T) { testClientHead(t, false) }
+func TestClientHead_h2(t *testing.T) { testClientHead(t, true) }
+
+func testClientHead(t *testing.T, h2 bool) {
 	defer afterTest(t)
-	ts := httptest.NewServer(robotsTxtHandler)
-	defer ts.Close()
+	cst := newClientServerTest(t, h2, robotsTxtHandler)
+	defer cst.close()
 
-	r, err := Head(ts.URL)
+	r, err := cst.c.Head(cst.ts.URL)
 	if err != nil {
 		t.Fatal(err)
 	}