clean up git after leanproject get-mathlib-cache

[kckennylau]

Feature request: have leanproject get-mathlib-cache execute at the end:

git reset --hard [commit id specified by leanpkg.toml]
git clean -fd

[gebner]

I'm very strongly against this change. Most of my mathlib clones have untracked files in them that should not be committed (like bug reports from Zulip, etc.). This change would delete them without warning.

[PatrickMassot]

We certainly can't run git clean -fd when editing mathlib itself.

[PatrickMassot]

I think Kenny wanted to run this inside _target/deps/mathlib, which is currently completely removed when updating.

[kckennylau]

yeah this is meant to be for a repo that depends on mathlib, rather than mathlib itself

[PatrickMassot]

Fixed in b1e6d66