import from alias resolves incorrect relative path

[m4rvr]

Describe the bug

After I have upgraded to 1.0.0-beta.4 the imports to my aliased packages e.g. @scope/pkg doesn't work.
The import paths are incorrect relative paths.

Before:
'/@/packages/test/src/index.ts'

After:
/../packages/test/src/index.ts

Info

The vite.config.ts is in the root, the playground is the directory from where I import the packages.
What I have found out is that the path is wrong after it has run through path.relative() here.

Reproduction

Reproduction

System Info

• vite version: 1.0.0-beta.4
• Operating System: Windows 10