Bug description

When using rollup to build a project, babel polyfills typeof for the AsyncIterator. This fails on Windows in a monorepo because of broken paths.

Command

yarn workspace core build

I already created an issue in the rollup package, but was refered here: rollup/plugins#290

What is the current behavior?

The resolved path is missing backslashes:

C:UsersjohanneszProjectsMyproject
untime/helpers/typeof (imported by ..\..\..\node_modules\regenerator-runtime\runtime.js,  C:UsersjohanneszProjectsMyproject
untime/helpers/typeof?commonjs-external

What is the expected behavior?

The correct resolved path.

Steps to Reproduce

1. git clone https://github.com/johannes-z/rollup-yarn-path-error
2. yarn
3. yarn workspace core build

Environment

• Node Version: 11.13.0
• Yarn v1 Version: 1.22.0
• OS and version: Windows 10