Revert hardcoded nightly version

[ecton]

Code coverage started failing recently, and it appears that it's due to an ICE that dates back a little bit, but only recently started cropping up most likely due to rustfmt being broken on nightly for a while: . I tried to narrow it down, but I can't seem to get the ICE to occur outside of the project.

The earliest version of nightly that installed all the default components that doesn't cause an ICE is 2021-03-25.

The commit to revert is: cd668bf

[richkadel]

There was a recent change that landed in nightly just a couple of days ago that started causing an ICE for certain macro invocations. I suspect this is the issue you noticed.

I've submitted a pull request to fix it: rust-lang/rust#84456

It's approved and should be in nightly in a couple of days or so.

[ecton]

Thanks for the update, I can confirm that what I was whittling down seemed related to macros. And, more importantly, thank you for contributing a fix!