title: create react app default port env
body: <p>I'm trying to change the default port being used by create react app. If I use "start": "PORT=4000 react-scripts start" and restart the server, it works fine. But using "start": "process.env.REACT_APP_PORT react-scripts start" returns undefined. My .env.development file has REACT_APP_PORT=4000 and I can console log the port from index.js, so it does seem to be set OK at that point</p>