pycompat: change users of pycompat.{stdin,stdout,stderr} to use procutil.std*
On Python 3, pycompat.{stdin,stdout,stderr} are usually block-buffered even if
connected to a TTY. procutil.{stdin,stdout,stderr} provide consistent behavior
across platforms and Python versions.
#require black
$ cd $RUNTESTDIR/..
$ black --config=black.toml --check --diff `hg files 'set:(**.py + grep("^#!.*python")) - mercurial/thirdparty/**'`