help: clarify behavior of server.concurrent-push-mode
So it doesn't seemingly say that old clients cannot talk to server
configured with concurrent-push-mode=check-related. They can, they
just don't get the benefit.
Differential Revision: https://phab.mercurial-scm.org/D8201
[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
'''
skip-string-normalization = true
quiet = true