def gzipped_tarball
      gz = StringIO.new("")
      z = Zlib::GzipWriter.new(gz, compression_level)
      z.write(tarball.string)
      z.close

      # z was closed to write the gzip footer, so
      # now we need a new StringIO
      StringIO.new(gz.string)
    end
def gzipped_tarball
      gz = StringIO.new("")
      z = Zlib::GzipWriter.new(gz, compression_level)
      z.write(tarball.string)
      z.close

      # z was closed to write the gzip footer, so
      # now we need a new StringIO
      StringIO.new(gz.string)
    end
Create the gzipped tarball. See {#tarball} for how the tarball is
 constructed. This method uses maximum gzip compression, unless the user
 specifies a different compression level.

 @return [StringIO]