hghave: update rustfmt criterion...
hghave: update rustfmt criterion
In
9ebc10ad4a04 I updated `rustfmt` without touching hghave, which means
that the CI has been skipping the format test ever since. Thankfully, only
one offending line exists in the code that's been introduced since.
Differential Revision:
https://phab.mercurial-scm.org/D12180
