if m == nil {
		return false
	}
	cache := m
	switch {
	case !cache.finished() && time.Since(cache.lastUpdate) > metacacheMaxRunningAge:
		// Not finished and update for metacacheMaxRunningAge, discard it.
		return false
	case cache.finished() && time.Since(cache.lastHandout) > 5*metacacheMaxClientWait:
		// Keep for 15 minutes after we last saw the client.