gistfile1.rb

# in lib/asset_tag_helper_ext.rb
module ActionView
  module Helpers
    module AssetTagHelper

      alias :orig_javascript_include_tag :javascript_include_tag
      def javascript_include_tag(*sources)
        options = sources.extract_options!.stringify_keys
        rkey = '__scripts'
        request[rkey] ||= []
        scripts = request[rkey]
        ok = []
        sources.each do |src|
          if !scripts.include?(src.to_s)
            scripts << src.to_s
            ok << src
          end
        end
        request[rkey] = scripts
        orig_javascript_include_tag(ok, options)
      end

      alias :orig_stylesheet_link_tag :stylesheet_link_tag
      def stylesheet_link_tag(*sources)
        options = sources.extract_options!.stringify_keys
        rkey = '__styles'
        request[rkey] ||= []
        styles = request[rkey]
        ok = []
        sources.each do |src|
          if !styles.include?(src.to_s)
            styles << src.to_s
            ok << src
          end
        end
        request[rkey] = styles
        orig_stylesheet_link_tag(ok, options)
      end

    end
  end
end