tests/helper-runtests.sh

test-check: don't report distutils as a local import

On python 3.12 this is wrongly reported as a local import. So we adjust the
checker to avoid it.

#
# Avoid interference from actual test env:

unset HGTEST_JOBS
unset HGTEST_TIMEOUT
unset HGTEST_PORT
unset HGTEST_SHELL