procutil: make recent fix for zombies compatible with py2
The fix in
ed684a82e29b (procutil: always waiting on child processes
to prevent zombies with 'hg serve', 2020-05-07) works only on Python 3
because it passes a `daemon` argument to `threading.Thread()`. Python
2 requires you to assign to the `.daemon` property instead. Python 3
also seems to support that, so this patch fixes the code by
unconditionally using the old form.
Differential Revision: https://phab.mercurial-scm.org/D8657
$ hg init
$ touch unknown
$ touch a
$ hg add a
$ hg ci -m "1"
$ touch b
$ hg add b
$ hg ci -m "2"
Should show unknown
$ hg status
? unknown
$ hg revert -r 0 --all
removing b
Should show unknown and b removed
$ hg status
R b
? unknown
Should show a and unknown
$ ls -A
.hg
a
unknown