tests: use native string type for parsed hghave log lines
Before this change, on Python 2, the parsed messages were decoded to unicode,
causing an implicit conversion from unicode to str later.
[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
'''
skip-string-normalization = true
quiet = true