message: nydus-image: ensure v6 to use aligned chunk
  Nydus v6 needs "aligned chunk" to make sure kernel fs can read blob
  cache files correctly.
diff: @@ -389,7 +389,6 @@ struct Command {}
  impl Command {
  fn create(matches: &clap::ArgMatches, build_info: &BuildTimeInfo) -> Result<()> {
  - let aligned_chunk = matches.is_present("aligned-chunk");
  let blob_id = Self::get_blob_id(&matches)?;
  let bootstrap_path = Self::get_bootstrap(&matches)?;
  let chunk_size = Self::get_chunk_size(&matches)?;
  @@ -403,6 +402,13 @@ impl Command {
  let blob_stor = Self::get_blob_storage(&matches, source_type)?;
  let repeatable = matches.is_present("repeatable");
  let version = Self::get_fs_version(&matches)?;
  + let aligned_chunk = if version == RafsVersion::V6 {
  + info!("v6 enforces to use \"aligned-chunk\".");
  + true
  + } else {
  + // get_fs_version makes sure it's either v6 or v5.
  + matches.is_present("aligned-chunk")
  + };
  let whiteout_spec: WhiteoutSpec = matches
  .value_of("whiteout-spec")
  .unwrap_or_default()
  