// newer version is available.
func prepareUpdateMessage(downloadURL string, older time.Duration) string {
	if downloadURL == "" || older <= 0 {
		return ""
	}

	// Compute friendly duration string to indicate time
	// difference between newer and current release.
	t := time.Time{}
	newerThan := humanize.RelTime(t, t.Add(older), "before the latest release", "")

	if globalServerCtxt.JSON {