dirstate: handle missing backup file on restoration
This is the stable counter part to e358f6e0e50e.
Since 6.4 will stop writing undo.dirstate in some case (actually… at all), a
transaction created with 6.4 and recover/rolledback with 6.3 need to work to a
certain degreee. This changeset add the necessary bits so that we don't get a
traceback from 6..3 in this cases.
[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