message: fix: downloader not work for url without eTag
diff: @@ -364,13 +364,13 @@ export class HttpDownloader implements Downloader {
  let update = async () => {
  let newMetadata = await this.resolveMetadata(originalUrl);
  let unmatched = newMetadata.eTag !== eTag;
  - if (unmatched) {
  + if (unmatched || newMetadata.eTag === undefined) {
  url = newMetadata.url;
  eTag = newMetadata.eTag;
  - total = newMetadata.contentLength;
  acceptRanges = newMetadata.acceptRanges;
  - resolvedUrl = parse(url);
  + total = newMetadata.contentLength;
  await truncate(fd, total);
  + resolvedUrl = parse(url);
  reset();
  }
  }
  