bug of switching vue version with pnpm

[jackson-yyy]

demo:
https://github.com/jackson-yyy/vue-demi-bug-demo

reproduce steps

1. run pnpm install
2. check node_modules/lib/v3/index.cjs, it is correct.

var Vue = require('vue')

Object.keys(Vue).forEach(function(key) {
  exports[key] = Vue[key]
})

3. run pnpm switch:vue2
4. check node_modules/lib/v3/index.cjs, it becomes the source code of v2. it shouldn't be changed.

var Vue = require('vue')
var VueCompositionAPI = require('@vue/composition-api')

i think it's the problem of pnpm. It use symbol link to link file.

i try to delete files under lib before writing file

function copy(name, version, vue) {
  vue = vue || 'vue'
  const src = path.join(dir, `v${version}`, name)
  const dest = path.join(dir, name)
  let content = fs.readFileSync(src, 'utf-8')
  content = content.replace(/'vue'/g, `'${vue}'`)
+ fs.unlinkSync(dest)
  fs.writeFileSync(dest, content, 'utf-8')
}

it works perfectly now.