The tag is present in Lintian version 2.113.26. That is the most recent version we know about.
We use semantic versions.
The patch number is a commit step indicator relative to the
release tag in our Git
You can find the detection logic for this version at commit 43a81d7. For merge requests, please use the latest version in the Lintian check scripts.
The maintainer script apparently runs install-sgmlcatalog. install-sgmlcatalog is deprecated and should only have been used in postinst or prerm to remove the entries from earlier packages. Given how long ago this transition was, consider removing it entirely.