rhg: add error message for paths outside the repository when cwd != root
This mirrors the Python implementation.
The relative path handling should probably be refactored into a util, but it
it out of scope for this change.
[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