fetch_spec

# File lib/rubygems/source.rb, line 138
  def fetch_spec name_tuple
    fetcher = Gem::RemoteFetcher.fetcher

    spec_file_name = name_tuple.spec_name

    uri = api_uri + "#{Gem::MARSHAL_SPEC_DIR}#{spec_file_name}"

    cache_dir = cache_dir uri

    local_spec = File.join cache_dir, spec_file_name

    if File.exist? local_spec then
      spec = Gem.read_binary local_spec
      spec = Marshal.load(spec) rescue nil
      return spec if spec
    end

    uri.path << '.rz'

    spec = fetcher.fetch_path uri
    spec = Gem.inflate spec

    if update_cache? then
      FileUtils.mkdir_p cache_dir

      File.open local_spec, 'wb' do |io|
        io.write spec
      end
    end

    # TODO: Investigate setting Gem::Specification#loaded_from to a URI
    Marshal.load spec
  end