tests/helper-runtests.sh

py3: have pycompat.ospathsep and pycompat.ossep

We needed bytes version of os.sep and os.pathsep in py3 as they return
unicodes.

#
# Avoid interference from actual test env:

unset HGTEST_JOBS
unset HGTEST_TIMEOUT
unset HGTEST_PORT
unset HGTEST_SHELL