code: function patchAssignSocket (res, callback) {
    var assignSocket = res.assignSocket
  
    if (typeof assignSocket !== 'function') return
  
    // res.on('socket', callback) is broken in 0.8
    res.assignSocket = function _assignSocket (socket) {
      assignSocket.call(this, socket)
      callback(socket)
    }
  }
docs: Patch ServerResponse.prototype.assignSocket for node.js 0.8.
  
  @param {ServerResponse} res
  @param {function} callback
  @private
   istanbul ignore next: node.js 0.8 patch