Prune babel-loader's cache so it does not grow forever

[gdborton]

I'm submitting a feature request
Would it be possible to add a way to prune the babel-loader cache after webpack runs? We've started uploading/downloading our cache in CI to help performance across builds, but the babel-cache grows unbounded and eventually bogs down our CI.

Babel Loader Version:
7.1.4

Current behavior:
babel cache grows unbounded

Expected/desired behavior:
It doesn't.

[loganfsmyth]

We could consider having some kind of LRU prune step the first the time loader runs in a given process, or something. It's a little ugly no matter what unfortunately.

[gdborton]

Agreed about the ugliness, especially since we can have more than one compiler/process trigger babel-loader.