debugtagscache: verify that filenode is correct
Previous patch from Matt demonstrates that `debugtagscache` does not warn about
filenode being unknown which can be caused by a corrupted cache.
We start by showing that it's an unknown node.
Differential Revision: https://phab.mercurial-scm.org/D10015
[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
'''
skip-string-normalization = true
quiet = true