class Gem::Package::TarWriter

def mkdir(name, mode)
  check_closed
  name, prefix = split_name(name)
  header = Gem::Package::TarHeader.new name: name, mode: mode,
                                       typeflag: "5", size: 0,
                                       prefix: prefix,
                                       mtime: Gem.source_date_epoch
  @io.write header
  self
end