message: use app.setAssetPrefix() in the server
diff: @@ -9,18 +9,21 @@ const port = parseInt(process.env.PORT, 10) || 3001
  const app = next({dev: process.env.NODE_ENV !== 'production'})
  const handle = app.getRequestHandler()
  +const deployURL = process.env.NOW_URL || ''
  +const deployHost = parse(deployURL).host
  +
  const staticDir = join(__dirname, 'static')
  app.prepare().then(() => {
  createServer((req, res) => {
  const parsed = parse(req.url, true)
  - const path = join(staticDir, parsed.pathname)
  - if (existsSync(path)) {
  - app.serveStatic(req, res, path)
  - } else {
  + const {host} = req.headers
  + const baseURL = deployHost && host !== deployHost ? deployURL : ''
  + // set the asset prefix to the deployed URL if the Host header differs
  + app.setAssetPrefix(baseURL)
  handle(req, res, parsed)
  - }
  - }).listen(port, err => {
  + })
  + .listen(port, err => {
  if (err) throw err
  console.log(`> Ready on http://localhost:${port}`)
  })
  