Update home usage to new env fn

[LucioFranco]

This is the corresponding PR for brson/home#29 which updates how rustup uses the home crates Env features for testing.

This is still a draft PR pending a new release of the home crate with the new features.

cc @kinnison

[rbtcollins]

Sure, looks fine I guess - aesthetically it has stuttering. I realise this isn't a rust style guide issue but it is one that I find very helpful in making nice APIs. (And not the extreme version presented in some golang talks!).

But not having to maintain home is much more beneficial than a few extra env:s here and there.

That said, I think this would be a smaller patch if instead of the insertion of ::env you added use home::env as home at the top of each affected source file.

[LucioFranco]

That said, I think this would be a smaller patch if instead of the insertion of ::env you added use home::env as home at the top of each affected source file.

Oh that is a great idea, I didn't think of that, will make that change.

[kinnison]

As it stands, I think that this is clean and clear. Once a new home release is done, I look forward to this being updated for the new home version.

[LucioFranco]

Hm I feel like the ring failure has nothing to do with my changes?

[hi-rustin]

Hm I feel like the ring failure has nothing to do with my changes?

Yes. See: rust-lang/rust#102332 (comment)

[hi-rustin]

Thanks!