tests/helper-runtests.sh

tests: add bytes prefixes to test-histedit-fold.t's local extension

# skip-blame b prefixes

Differential Revision: https://phab.mercurial-scm.org/D2246

#
# Avoid interference from actual test env:

unset HGTEST_JOBS
unset HGTEST_TIMEOUT
unset HGTEST_PORT
unset HGTEST_SHELL