fix: yarn v1 downloading empty cli

[eps1lon]

What's the problem this PR addresses?

yarn policies set-version v2 creates a file with the content false since https://github.com/yarnpkg/berry/raw/master/packages/berry-cli/bin/berry.js returns 404. Issue was caused by #395

How did you fix it?

Create a symlink from the old cli file to the current location

Which packages would need a new release (if any)?

If any then the v1 cli should get a patch. Though this approach has the benefit that it is immediate and backports the fix.

Have you run yarn version prerelease in those packages?

• [ ] Yes

[eps1lon]

Additional note: The v1 cli should throw if the download returned no success status code.

[eps1lon]

@arcanis Sorry just tried but github doesn't follow symlinks. You just get ../../yarnpkg-cli/bin/yarn.js.

Upside: Error is thrown instead of yarn nooping.

[arcanis]

@eps1lon should be fixed (use berry instead of v2 though).

[eps1lon]

@eps1lon should be fixed (use berry instead of v2 though).

Should we change https://yarnpkg.github.io/berry/getting-started/install ?

[arcanis]

Yep, that sounds like a good idea!