Zobel gave me a nice tip.
Step 1:
scp master.debian.org:/etc/ssh/ssh_known_hosts ~/.ssh/debian_known_hosts
Step 2:
Host *.debian.org UserKnownHostsFile ~/.ssh/debian_known_hosts
Step 3: update ~/.ssh/debian_known_hosts
every once in a while.
Thank you Zobel, this makes me happy.