tests/helper-runtests.sh

py3: use bytes literal in test-hgweb-json.t

# skip-blame just b'' prefix

Differential Revision: https://phab.mercurial-scm.org/D4970

#
# Avoid interference from actual test env:

unset HGTEST_JOBS
unset HGTEST_TIMEOUT
unset HGTEST_PORT
unset HGTEST_SHELL