test-dirstate: fix detection of Rust environment variable The Rust path never actually worked. This change also improves clarity of the comment. The next change will ensure we print something when this check fails. Differential Revision: https://phab.mercurial-scm.org/D12601

[build-system]
requires = ["setuptools", "wheel"]

[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
'''
skip-string-normalization = true
quiet = true