Custom relative path assetPrefix breaks with locales

[AlexW-Valtech]

What version of Next.js are you using?

10.0.9

What version of Node.js are you using?

14.15.4

What browser are you using?

Chrome

What operating system are you using?

Windows

How are you deploying your application?

Local development

Describe the Bug

We will have several next.js applications sitting under the same domain, so will want to prefix _next requests. As referenced in #5602 (comment), we are using this method:

module.exports = {
  assetPrefix: '/docs',
  rewrites() {
    return [
      { source: '/docs/_next/:path*', destination: '/_next/:path*' }
    ]
  }
}

This works until we add locales, even with just one:

module.exports = {
  assetPrefix: '/docs',
  i18n: {
    locales: ['en-gb'],
    defaultLocale: 'en-gb'
  },
  rewrites() {
    return [
      { source: '/docs/_next/:path*', destination: '/_next/:path*' }
    ]
  }
}

At this point, the rewrite does not seem to happen at all and a request such as /docs/_next/static/chunks/pages/_app.js?ts=1616407895355 results in a 404.

Expected Behavior

The rewrite for the prefixed assetPath is expected to work.

To Reproduce

1. Use configuration applied above
2. Run local development server
3. See 404s for the asset requests

[jankaifer]

Hi does this still happen in next@canary?
And could you provide a repo I can clone if it does? It will save us a lot of time when we are digging into this.

[balazsorban44]

This issue has been automatically closed because it wasn't verified against next@canary. If you think it was closed by accident, please leave a comment. If you are running into a similar issue, please open a new issue with a reproduction. Thank you.

[github-actions]

This closed issue has been automatically locked because it had no new activity for a month. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.