Route pushRouter makes app refresh

Hi!

I have a problem when trying to redirect the page. I don't want to refresh the page when push router! But for now, it still reloads the page in case I add language prefix (eg: 'en-us') into the route.
Please note that: if routes don't have language prefix (eg: '/ride-input') => locale is ja-jp.
Defined routes:
```
routes.
.add('category', '/category')
```
pushRoute:
```
Router.pushRoute('/en-us/category')
```

Error when pushRoute:

GET http://localhost:9006/_next/static/development/pages/en_us/category.js net::ERR_ABORTED 404 (Not Found)
Navigated to http://localhost:9006/en_us/category

fridays / next-routes

Route pushRouter makes app refresh #330