message: Nydusify: fix incorrect layer diff id check in cache image
  The blob layer is uncompressed, so just append blob digest to the
  diff id list in the cache image.
diff: @@ -257,10 +257,16 @@ func (cache *Cache) Export(ctx context.Context) error {
  layers := cache.exportRecordsToLayers()
  // Ensure layers from manifest match with image config,
  - // this will keep image compatibility when using docker pull.
  + // this will keep compatibility when using docker pull
  + // for the image that only included bootstrap layers.
  diffIDs := []digest.Digest{}
  for _, layer := range layers {
  - diffID := digest.Digest(layer.Annotations[utils.LayerAnnotationUncompressed])
  + var diffID digest.Digest
  + if layer.MediaType == utils.MediaTypeNydusBlob {
  + diffID = layer.Digest
  + } else {
  + diffID = digest.Digest(layer.Annotations[utils.LayerAnnotationUncompressed])
  + }
  if diffID.Validate() == nil {
  diffIDs = append(diffIDs, diffID)
  } else {
  