tests: add a test to demonstrate a bug in `hg diff --git` (issue6486)
Issue url: https://bz.mercurial-scm.org/show_bug.cgi?id=6486
This will be fixed in next patch.
Differential Revision: https://phab.mercurial-scm.org/D10000
[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
'''
skip-string-normalization = true
quiet = true