Jest does not seem to properly handle process.env.TZ: Setting process.env.TZ does not affect Dates

To reproduce:

1. Install dependencies

   npm ci
   

2. Run the tests; this demonstrates the bug

   npm test
   

3. Run the tests with TZ=UTC; the TZ=EST test will fail

   TZ=UTC npm test
   

4. Run the tests with TZ=EST; the TZ=UTC test will fail

   TZ=EST npm test
   

Workarounds

• The TZ environment variable can be overridden directly in jest.config.js (https://stackoverflow.com/a/58238786/399105)

• Use Jest's setupFiles configuration option to point to a setup file that sets TZ (https://stackoverflow.com/a/58953365/399105)

• Hardcode TZ in any scripts in package.json that call Jest, e.g.

  "scripts": {
    "test": "TZ=UTC jest",