Patch to fix MissingTemplate issue in Rails 3

missing_template_fix.rb

module ActionController
  module ImplicitRender

    def default_render
      # lookup template exist? go to render it
      render and return if template_exists?(action_name.to_s, _prefix)

      has_template = begin
        old_formats, @lookup_context.formats = @lookup_context.formats, Mime::SET.symbols
        template_exists?(action_name.to_s, _prefix)
      ensure
        @lookup_context.formats = old_formats
      end

      # if lookup template not exist then go to check if any template existed,
      # if so show 406, if not, go render, it will give MissingTemplate error.
      has_template ? head(:not_acceptable) : render
    end

  end
end