worker-load.js conflicts with fetch-load.js and prevents systemjs-babel from working in a web worker

[Jens Lincke]

fetch-load.js and worker-load.js are incompatible and overwrite each other.

The https://github.com/systemjs/systemjs-babel extension uses the fetch-load and therefore does not function in a web worker.

Is this the intended behavior or a bug? Was it the correct place for systemjs-babel to hook into code rewriting? Or should worker-load.js behavior be fixed?