tests: show that in-memory rebase leaves state when working copy is dirty
When in-memory rebase falls back to on-disk rebase, it checks if the
working copy is dirty. If it is, it aborts the rebase. However, it
leaves the rebase state on disk. I broke it in feffeb18d412 (rebase:
teach in-memory rebase to not restart with on-disk rebase on conflict,
2020-09-18).
Differential Revision: https://phab.mercurial-scm.org/D9508
[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
'''
skip-string-normalization = true
quiet = true