redirect() is not correct working with base path

[NikolayMakhonin]

I can reproduce this bug in Opera 58, Chrome 33, Chrome 74 Dev. And only if I go the link from address bar. Click by link is worked correctly.

I set base path as /sapper/page - site worked correctly.
Then added this code to the routes/index.html

export default {
    preload() {
        return this.redirect(302, 'login')
    }
}

Actual redirect behavior:
http://localhost:3000/sapper/page ==> http://localhost:3000/sapper/login
but I expected this:
http://localhost:3000/sapper/page ==> http://localhost:3000/sapper/page/login

---

I can fix this bug if I change follow line in the file __sapper__/server.js:

if (redirect) {
    console.log(req.baseUrl);
    // const location = url.resolve(req.baseUrl || '/', redirect.location); // Original
    const location = url.resolve((req.baseUrl || '') + '/', redirect.location); // Changed
    res.statusCode = redirect.statusCode;
    res.setHeader('Location', location);
    res.end();
    return;
}

[arxpoetica]

#593 also seems to be related, if not indirectly