``this.request.query`` is empty in original koa middleware

[zhengyhn]

Here is my code.

const koa = require('koa.io')
const app = koa()
// if I use the original 'koa', it's ok
// const app = require('koa')()

const Router = require('koa-router')
const router = new Router()
router.get('/test', function * () {
    console.log(this.query);                  // output {}
    console.log(this.request.query);     // output {}
})
app.use(router.routes())

Thanks.