What about rustfmt? Rust 1.23 included rustfmt and not cargo-fmt, and this was an unannounced secret feature. Is rustfmt fully ready now? If so, we should yell about it (and incremental compilation) from the mountaintops!
This release does include both cargo-fmt and rustfmt with the rustfmt-preview component. I’m not sure it’s something to put in the release notes, but I’ll ask @steveklabnik to include it in the blog post if we feel it’s ready.
As for the cargo working directory change, I think we’ve decided to land this and deal with the breakage. It’s unfortunate, but the Cargo team feels/felt that the breakage was warranted for the bug fix of no longer recompiling when we changed working directories. We’ll continue pushing on the issues you mentioned, though, and it seems likely that by 1.26 they’ll be ready to go (though no guarantees).