tests/helper-runtests.sh

revlog: simplify rawtext return value

We're always returning a tuple even though only the raw text is being used,
and we're rebuilding another tuple again higher.

As a bonus, this will remove one tuple creation and deletion
per `raw_text` call, hence fewer gc calls, etc.

#
# Avoid interference from actual test env:

unset HGTEST_JOBS
unset HGTEST_TIMEOUT
unset HGTEST_PORT
unset HGTEST_SHELL