histedit: add missing b prefix to a string
If i18n is disabled (such as via HGPLAIN=1), `_()` doesn't convert from str to
bytes, so this raises a TypeError on py3.
Differential Revision: https://phab.mercurial-scm.org/D8354
[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
| contrib/python-zstandard/
'''
skip-string-normalization = true
quiet = true