Include CACHEDIR.TAG file in our cache directory

[lagru]

Description:

scikit-image creates a cache directory with skimage.data.download_all. We should probably include a CACHEDIR.TAG file inside to mark it as such. See https://bford.info/cachedir/. As far as I am aware it's not an official spec or anything (yet). But pytest / mypy already do so, and there's discussion to do it for cpython. So if we get around to it, it's easy enough to do...

[mkcor]

Upvoting 👍

I wasn't aware of this convention, thanks for sharing!

[stefanv]

CACHEDIR.TAG is fine to add; just had to 🙄 at:

This signature header is required to avoid the chance of an unrelated file named CACHEDIR.TAG being mistakenly interpreted as a cache directory tag by data management utilities, and (for example) causing valuable data not to be backed up.