if !strings.HasPrefix(b, line) {
			return a, b, commonLines
		}
		commonLines++
		a = a[len(line):]
		b = b[len(line):]
	}
}

func TestClientRedirectUseResponse(t *testing.T) { run(t, testClientRedirectUseResponse) }
func testClientRedirectUseResponse(t *testing.T, mode testMode) {
	const body = "Hello, world."
	var ts *httptest.Server
	ts = newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {