merge: remove direct rustmod reference
We shouldn't rely on this member being present in `dirstate.py`, this creates
unnecessary coupling.
This also can trigger certain issues in edge-cases where the policy is changed
at runtime or multiple Python environments fight, which is an added bonus.
Differential Revision: https://phab.mercurial-scm.org/D12217
#require rustfmt test-repo
$ . "$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
> done