tags: show how hg behaves if a tags cache entry is truncated
I'm seeing an error of this form in production on the order of once a
month. I'm not sure how it happens, but I suspect interrupting a pull
might result in half written cache entries.
Differential Revision: https://phab.mercurial-scm.org/D8094
[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
'''
skip-string-normalization = true
quiet = true