Fix CI failures

[topecongiro]

https://travis-ci.com/rust-lang/rustfmt cargo install --path . --force is failling due to picking up the latest crossbeam-channel which is apparently broken with the latest nightly.

Possibly related: rust-lang/cargo#7169.

[calebcartwright]

crossbeam-rs/crossbeam#435 - looks like they've already fixed crossbeam-channel but have't released the new version yet

[topecongiro]

Yes, it looks like cargo has changed its behavior when passed install --path and ignores the Cargo.lock file. I added --locked in the script in #3889 to force cargo to use the dependencies specified in the Cargo.lock.

[calebcartwright]

Looks like a new 0.4.0 version of crossbeam-channel and a 0.7.0 version of crossbeam-utils have been published with the fix. Would it be worth updating the lockfile with these new versions?

[topecongiro]

Yes!

[calebcartwright]

Will open a PR in a bit with those bumps

[calebcartwright]

Unfortunately it seems that ignore is pinned on crossbeam-channel v0.3.6 which in turn has a ^v0.6.5 dependency on crossbeam-utils, basically preventing updating either.

I'll follow up with an issue over in ignore