with_layout_format

# File actionpack/lib/action_view/lookup_context.rb, line 183
      def with_layout_format
        if formats.size == 1
          yield
        else
          old_formats = formats
          _set_detail(:formats, formats[0,1])

          begin
            yield
          ensure
            _set_detail(:formats, old_formats)
          end
        end
      end