Control: tags -1 confirmed, moreinfo Hello!
Yes, technically I could do a backport for Buster. Note however that doing so would create a package that replaces rdiff-backup 1.0 on the next 'apt upgrade' and there might be some backwards incompatible changes. I'd like to have more people voice in here if there is really demand for this. You could perhaps also installing a backport from the Ubuntu backports: https://github.com/rdiff-backup/rdiff-backup#ubuntu-backports-for-older-versions-needs-a-backported-20