Shut down connections that haven't even identified themselves as git
clients first. That should get rid of people who just connect to the
port and wait for something to happen.
This is using a lockless approach that allows us to handle children
dying without having to block SIGCHLD.
Right now our "solution" to too many kids is pretty damn rough, but it
at least shows what you can do.
Alexey Nezhdanov sent a patch that made git-daemon usable from inetd (ie
where inetd has already done the accept on the new connection, the fork,
and the setup of stdin/stdout). I wanted to organize the thing slightly
differently, though.
