[Bug] yarn-path in .yarnrc is not set using standardized path separators

[MLoughry]

Describe the bug

When running yarn policies set-version berry in a repository on a Windows machine, this will set the yarn-path using Windows path separators, like so:

# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
# yarn lockfile v1


lastUpdateCheck 1562702253233
yarn-path ".yarn\\releases\\yarn-berry.js"

Then, when you attempt to run yarn on a *nix machine, you get an error:

Error: Cannot find module '/home/vsts/work/1/s/.yarn\releases\yarn-berry.js'
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:636:15)
    at Function.Module._load (internal/modules/cjs/loader.js:562:25)
    at Function.Module.runMain (internal/modules/cjs/loader.js:829:12)
    at startup (internal/bootstrap/node.js:283:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:622:3)

To Reproduce

Migrate a repository to yarn berry on a Windows machine. You can see the .yarnrc immediately, or run it on a *nix machine to see the resulting error.

Screenshots

If applicable, add screenshots to help explain your problem.

Environment if relevant (please complete the following information):

• OS: Windows
• Node version 12.4.0
• Yarn version 2.0.0

Additional context

This seems like a simple enough bug that I was going to submit my own PR, but I can't seem to find where this is set. Is this bug in the release version of yarn?

[arcanis]

Hm interesting - this particular fix should be done in the v1 trunk, since it's the one that generates and reads the yarn-path field in this situation (right before shelling out to the local binary):

https://github.com/yarnpkg/yarn/blob/master/src/cli/commands/policies.js#L158

[paul-soporan]

This isn't a problem anymore (after yarnpkg/yarn#7931), so I'm going to close this issue.