Judge CommonJS package that use scope on Windows incorrectly

[zhoudewei2526]

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Describe the bug

It is incorrect to judge whether the package is CommonJS On Windows 。And the npm package uses scope(like @vhook/test) .

Reproduction

repository link

System Info

• vite version: 2.0.0-beta.35
• Operating System: Windows
• Node version: 12.18.0
• Package manager (npm/yarn/pnpm) and version:
  yarn 1.16.0

Logs (Optional if provided reproduction)

1. Run vite or vite build with the --debug flag.
2. Provide the error log here.

[zhoudewei2526]

path.resolve return path segment separator is \ on Windows，but in metadata.json path segment separator is /
path.relative api

When I add .replace(/\\/g,'/'),it wroks .

[yyx990803]

closed via #1631