py3: use bytes stdout in hghave.py
This fixes a failure in test-run-tests.t around notarealhghavefeature. It seems
crazy to me that all of this needs to be adjusted in all of these tests, but the
line as run-tests.py sees it in _processoutput() before doing anything is
already mangled with a trailing '\r'. Switching to normalizenewlines=True for
TTest works, but I'm sure that breaks other stuff.
To run the tests, do:
cd tests/
python run-tests.py
See https://mercurial-scm.org/wiki/WritingTests for
more information on writing tests.