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 files/symbolic-links.
The named symbolic link in a source package resolves outside the shipped sources.
Please note that this tag is only issued for relative links targets. Absolute link targets are also disqualified because source packages are not anchored and can be unpacked anywhere. They triggers another tag.