The packaging scripts all assume port 22 when doing rsync, ssh, and scp. The pull request alonside this simply abstracts out the ssh port as an SSH_OPTS environment variable that can be set/overwritten by custom implementations.

Doesn't change existing functionality, but opens the door for a nonstandard port. The rationale is less about port security and more for implementation where the underlying host serving the files is now a docker container and we want to give rsync/ssh access to it and not to the host itself.