This repository is a little handy playground to test PR's before landing them to react-native repository.
If you have a custom fork of the react-native you need to keep it in sync with the main fork.
The best way to do it is contribute as many of your changes as possible. You probably don't use the latest and greatest version of react-native in production, so your changes might not work as you expect to on that version.
Feel free to use this playground to keep your PR's in working condition.