class ActionDispatch::FileHandler

def serve(request, filepath, content_headers)
  original, request.path_info =
    request.path_info, ::Rack::Utils.escape_path(filepath).b
  @file_server.call(request.env).tap do |status, headers, body|
    # Omit content-encoding/type/etc headers for 304 Not Modified
    if status != 304
      headers.update(content_headers)
    end
  end
ensure
  request.path_info = original
end