delta-find: clarify some comment and code in is_good_delta_info We move the comment closer to the code it describ and we compute an intermediate value without using the `textlen` variable, as it will stop being defined in a future patch. This will clarify future patches.

[build-system]
requires = ["setuptools", "wheel"]

[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
'''
skip-string-normalization = true
quiet = true