repoview: use the phasecache directly to determine mutable revisions This speeds up no-change updates from 1.3s to 0.85s for my NetBSD test repository. Differential Revision: https://phab.mercurial-scm.org/D8670

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