subsetmaker: use SortedSet for the scratch variant This provides a massive speedup on wide repository with many heads. For example on mozilla-try, this move from un-usable slow to fairly instant. Differential Revision: https://phab.mercurial-scm.org/D12395

[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