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 emacs
$ emacs -q -no-site-file -batch -l $TESTDIR/../contrib/hg-test-mode.el \
> -f ert-run-tests-batch-and-exit
Running 1 tests (*) (glob)
passed 1/1 hg-test-mode--compilation-mode-support
Ran 1 tests, 1 results as expected (*) (glob)