func newUnsignedV4ChunkedReader(req *http.Request, trailer bool) (io.ReadCloser, APIErrorCode) {
	if trailer {
		// Discard anything unsigned.
		req.Trailer = make(http.Header)
		trailers := req.Header.Values(awsTrailerHeader)
		for _, key := range trailers {
			req.Trailer.Add(key, "")
		}
	} else {
		req.Trailer = nil
	}
	return &s3UnsignedChunkedReader{
		trailers: req.Trailer,
		reader:   bufio.NewReader(req.Body),