[Bug] Yarn v2 - resolve package patching breaking change

[AlexandreBonaventure]

• I'd be willing to implement a fix

Describe the bug

As yarn v2 is now stable I took a shot at trying it on my current codebase. Some plugins that I use rely on resolve pkg (which ^1.9.0 is supported )
However, I'm noticing that yarn is changing the behaviour of the library, essentially it is not transparently patching the resolve pkg and breaks code that is working outside of yarn

To Reproduce
https://github.com/AlexandreBonaventure/yarn-berry-resolve-repro

1. git clone https://github.com/AlexandreBonaventure/yarn-berry-resolve-repro && cd yarn-berry-resolve-repro && yarn
   2a. node index.js SUCCESSFULLY RESOLVE
   2b. yarn node index.js ERROR

Screenshots

Environment

• OS: OSX 10.15.2
• Node version 11.12.0
• Yarn version 2.0.0-rc28

[AlexandreBonaventure]

After digging in source code I understand that the breaking change is introduced here :

berry/packages/plugin-compat/extra/resolve/normalize-options.js

Line 100 in 4ee0464

opts.paths = function (request, basedir, getNodeModulePaths, opts) {

where paths option is being completely overriden by pnp patch. One solution could be to smartly merge in the input paths option instead of staright up replacing it

[yarnbot]

Hi! 👋

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