}

// dialParallel races two copies of dialSerial, giving the first a
// head start. It returns the first established connection and
// closes the others. Otherwise it returns an error from the first
// primary address.
func (sd *sysDialer) dialParallel(ctx context.Context, primaries, fallbacks addrList) (Conn, error) {
	if len(fallbacks) == 0 {
		return sd.dialSerial(ctx, primaries)
	}

	returned := make(chan struct{})