    # File lib/action_view/helpers/asset_tag_helper.rb, line 155
          def image_path(source)
            unless (source.split("/").last || source).include?(".") || source.blank?
              ActiveSupport::Deprecation.warn(
                "You've called image_path with a source that doesn't include an extension. " +
                "In Rails 2.0, that will not result in .png automatically being appended. " +
                "So you should call image_path('#{source}.png') instead", caller
              )
            end

            compute_public_path(source, 'images', 'png')
          end