### Version 3.0.0-rc.8 ### Node and OS info node 10 / npm 6.1.10 / yarn 1.7.0 ### Steps to reproduce ```js module.exports = { baseUrl: '/test/' } ``` <img width="1347" alt="screen shot 2018-07-28 at 15 18 45" src="https://user-images.githubusercontent.com/187922/43356489-146e2caa-927a-11e8-8a94-d90ab904db60.png"> ### What is expected? - ### What is actually happening? WebSocket is closed before the connection is established. <!-- generated by vue-issues. DO NOT REMOVE -->