rust-index: core impl for find_gca_candidates and find_deepest
This still follows closely the C original and not able to treat more than 63
input revisions (bitset backed by `u64` and one bit reserved for poisoning).
[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