tests/helper-runtests.sh

wrapfunction: use sysstr instead of bytes as argument in "remotenames"

This is as valid and simpler, it will help us to eventually get ride of
`safehasattr`.

#
# Avoid interference from actual test env:

unset HGTEST_JOBS
unset HGTEST_TIMEOUT
unset HGTEST_PORT
unset HGTEST_SHELL