res, err := cst.c.Get(cst.ts.URL)
	if res != nil {
		defer res.Body.Close()
	}
	got := fmt.Sprint(err)
	wantSub := "too many 1xx informational responses"
	if !strings.Contains(got, wantSub) {
		t.Errorf("Get error = %v; want substring %q", err, wantSub)
	}
}

// Issue 26161: the HTTP client must treat 101 responses
// as the final response.