tests/helper-runtests.sh

changegroup: extract method that sorts nodes to send

The current implementation of narrowhg needs to influence the order in
which nodes are sent to the client. adgar@ and I think this is
fixable, but it's going to require pretty substantial time investment,
so in the interim we'd like to extract this method.

I think it makes the group() code a little more obvious, as it took us
a couple of tries to isolate the exact behavior we were observing.

#
# Avoid interference from actual test env:

unset HGTEST_JOBS
unset HGTEST_TIMEOUT
unset HGTEST_PORT
unset HGTEST_SHELL