tests/test-check-format.t

perf: drop an unnecessary `pass`

Differential Revision: https://phab.mercurial-scm.org/D7743

#require black

  $ cd $RUNTESTDIR/..
  $ black --config=black.toml --check --diff `hg files 'set:(**.py + grep("^#!.*python")) - mercurial/thirdparty/** - "contrib/python-zstandard/**"'`