dillon1000/react

[snap] patch bug in clearing require cache

Snap currently has a bug in which the require cache is not correctly cleared 
when running in filter mode (#tests < 2 * #workers). 

- We're currently clearing all entries in the require cache of worker threads, 
including `jest-worker` and `snap/dist/...` files 

- jest-worker seems to `require` these files on every dispatch (i.e. 
`worker.compile` seems to call `require(`compiler-worker`).compile`)