hgweb: do not try to replace signal handlers while locking
According to the issue 5889, mod_wsgi issues a warning on signal.signal()
call, and we wouldn't want to see it in error log. The problem addressed
by
d77c3b023393 could potentially occur in web session, but that would be
less likely than in user processes.
$ 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
unknown