Jest source maps not working

Hey there!

I'm pretty new to TypeScript/jest and I spent hours in figuring out why line numbering in failing tests are wrong so please bear with me.

I'm not sure if I missed something or it's an actual bug and I couldn't find anything close to my problem online. When running `install()`, line numbering breaks, when commenting it out, everything works fine (but of course stack traces don't work any more). It doesn't matter if `install()` is run in test code or in imported production code, test line numbering always breaks.

I have set up a demo repo over [here](https://github.com/schw4rzlicht/node-sourcemap-jest-demo).

Thanks for your help!