hg files 'set:**.py - mercurial/thirdparty/** - "contrib/python-zstandard/**" - hgext/fsmonitor/pywatchman/**' | xargs pyupgrade --keep-percent-format --keep-extraneous-parens
and then blackened. pyupgrade comes from
https://github.com/asottile/pyupgrade with a patch to let me preserve
extraneous parens (which we use for marking strings that shouldn't be
translated), and lets us clean up a bunch of idioms that have cruftily
accumulated over the years.
- skip-blame no-op automated code cleanups