rust-dirstatemap: add missing @propertycache
While investigating a regression on `hg update` performance introduced by the
Rust `dirstatemap`, two missing `@propertycache` were identified when comparing
against the Python implementation. This adds back the first one, that has
no observable impact on behavior. The second one (`nonnormalset`) is going to
be more involved, as the caching has to be done from the Rust side of things.
Differential Revision: https://phab.mercurial-scm.org/D8047
[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
| contrib/python-zstandard/
'''
skip-string-normalization = true
quiet = true