Lighttpd

My lighttpd.conf is:
...
server.max-worker = 4
server.pid-file = "/home/work/lighttpd/log/lighttpd.pid"
...

I start lighttpd, and check its running status:

$ pstree -p | grep lighttpd |-lighttpd(6895)-+-cronolog(6896) | |-lighttpd(6898)-+-{lighttpd}(6900) | | |-{lighttpd}(6901) | | |-{lighttpd}(6902) | | `-{lighttpd}(6903) | |-lighttpd(6899)-+-{lighttpd}(6906) | | |-{lighttpd}(6907) | | |-{lighttpd}(6908) | | `-{lighttpd}(6909) | |-lighttpd(6904)-+-{lighttpd}(6910) | | |-{lighttpd}(6911) | | |-{lighttpd}(6912) | | `-{lighttpd}(6913) | `-lighttpd(6905)-+-{lighttpd}(6914) | |-{lighttpd}(6915) | |-{lighttpd}(6916) | `-{lighttpd}(6917)

At this monent, the file "lighttpd.pid" was under "/home/work/lighttpd/log/".
However, after I killed process 6904, lighttpd.pid was deleted. It shouldn't had been removed by child processor.

This is a bug, I think.