tests/test-check-format.t

procutil: split if condition

This prepares the code for subsequent changes where we need to differentiate
between the two cases.

#require black

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