tests: avoid zombie lockup with test-hup
The 'while kill -0' recipe can cause a livelock if the process we're waiting
to die is a normal child process. If it becomes a zombie that the shell
doesn't reap (shell bug?), it will continue to be able to accept
signals. So instead, we just wait(1).
.. Common link and substitution definitions.
.. |hg(1)| replace:: **hg**\ (1)
.. _hg(1): hg.1.html
.. |hgrc(5)| replace:: **hgrc**\ (5)
.. _hgrc(5): hgrc.5.html
.. |hgignore(5)| replace:: **hgignore**\ (5)
.. _hgignore(5): hgignore.5.html