tests/helper-runtests.sh

py3: add b'' prefixes in tests/test-minirst.py

# skip-blame because just b'' prefixes

Differential Revision: https://phab.mercurial-scm.org/D2653

#
# Avoid interference from actual test env:

unset HGTEST_JOBS
unset HGTEST_TIMEOUT
unset HGTEST_PORT
unset HGTEST_SHELL