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.
i18n-de: synchronized with
fbdac607bff3
worker: properly report errors from worker processes (
issue3982)