run-tests: only lock Popen wait/poll on python 2.4
It can cause scheduling bubbles and is not necessary on newer pythons.
[ original upstream message ]
run-tests: lock popen wait/poll
In python2.4, any call to Popen() may attempt to wait on any active
process, and wait is not thread-safe. Make it thread-safe.
See http://bugs.python.org/issue1731717 for details.
[ original upstream message ]