Jest v22.0.6 always convert process.env array toString

I'm currently using yarn 1.3.2 and trying to migrate from jest 22.0.5 to latest version, but I did find a problem from v22.0.6

This is our very simple jest.config.js

module.exports = {
    setupFiles: ['./tools/test/setup.js']
}

And this is a simpler setup.js we use to debug this problem

const array = ['en', 'fr']
process.env.ARRAY = array
console.log('process.env.ARRAY', process.env.ARRAY)

In one of our test, we loop an process.env array and this is our output

22.0.5

console.log tools/test/setup.js:3
    process.env.ARRAY ['en', 'fr']

22.0.6

console.log tools/test/setup.js:3
    process.env.ARRAY en,fr

It seems that every process.env array to be converted with toString()

Do you have any idea what I am doing wrong?

Thanks!!