def unit_options
      options = {}
      return options unless manifest
      %i(root package_tool).each do |k|
        options[k] = manifest[k] unless manifest[k].nil?
      end
      options
    end
def unit_options
      options = {}
      return options unless manifest
      %i(root package_tool).each do |k|
        options[k] = manifest[k] unless manifest[k].nil?
      end
      options
    end
Load basic unit options from the manifest.
 @return [Hash] the options