Unable to release port after killed with SIGKILL

This is found with OpenSSH. Reproduce steps

sudo ion
/bin/sshd -D

In another terminal

ps # see sshd pid
kill 9 80
# also kill childs
kill 9 81
kill 9 83

After that, rerun /bin/sshd -D, you will see it exiting early. If you turn on debugging with /bin/sshd -D -ddd, this log appears:

debug1: Bind to port 22 on 0.0.0.0.
Bind to port 22 on 0.0.0.0 failed: Address already in use.
Cannot bind any address.

There's currently no workaround into this problem except reboot.