undo-files: cleanup legacy files when applicable
The "journal" code is much more compact in 6.4, and so is the "undo" files as a
result. However the previous version were much noisier, so let us cleanup undo
files from older version too.
[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