Comment 4 for bug 211180

Yes, I do have that option set, but it's not set for that particular host.

Host proxies
        UserKnownHostsFile /dev/null
        StrictHostKeyChecking no

Host *
        TCPKeepAlive no
        ServerAliveCountMax 3
        ServerAliveInterval 10
        ControlMaster no
        ControlPath ~/.ssh/%r-%h-%p-mux
        HashKnownHosts no

Note that for the host I'm talking about above (chizang.net), I don't even have an entry at all:

achiang@soy:~$ grep chizang .ssh/config
achiang@soy:~$