s2c, cb := newS2CompressReader(actualReader, actualSize, wantEncryption)
		idxCb = cb
		defer s2c.Close()
		reader = etag.Wrap(s2c, actualReader)
		size = -1   // Since compressed size is un-predictable.
		md5hex = "" // Do not try to verify the content.
		sha256hex = ""
	}

	var forceMD5 []byte

		s2c, idxCb = newS2CompressReader(actualReader, actualSize, wantEncryption)
		defer s2c.Close()

		reader = etag.Wrap(s2c, actualReader)
		size = -1   // Since compressed size is un-predictable.
		md5hex = "" // Do not try to verify the content.
		sha256hex = ""
	}

	var forceMD5 []byte