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

tests/hghave.py

@@ -1121,11 +1121,11 b' def has_pytype():'
     return version and sv(_bytes2sys(version.group(0))) >= sv('2019.10.17')
 
 
-@check("rustfmt", "rustfmt tool at version nightly-2020-10-04")
+@check("rustfmt", "rustfmt tool at version nightly-2021-11-02")
 def has_rustfmt():
     # We use Nightly's rustfmt due to current unstable config options.
     return matchoutput(
-        '`rustup which --toolchain nightly-2020-10-04 rustfmt` --version',
+        '`rustup which --toolchain nightly-2021-11-02 rustfmt` --version',
         b'rustfmt',
     )
 

tests/test-check-rust-format.t

@@ -3,6 +3,8 b''
   $ . "$TESTDIR/helpers-testrepo.sh"
 
   $ cd "$TESTDIR"/..
+
+Warning: Keep this in sync with hghave.py
   $ RUSTFMT=$(rustup which --toolchain nightly-2021-11-02 rustfmt)
   $ for f in `testrepohg files 'glob:**/*.rs'` ; do
   >   $RUSTFMT --check --edition=2018 --unstable-features --color=never $f