In the Salsa CI pipeline, if git-buildpackage fails to fetch the upstream tarball for whatever reason (git repository broken, missing branches, pristine-tar mismatch) it will fall back to run the origtargz command: https://manpages.debian.org/unstable/devscripts/origtargz.1.en.html
I would be careful in not having too much automation in case of pristine-tar failures. The person encountering them might be uncovering a true mismatch and the package history/sources might need to be audited to discover what/when wrong version was introduced. If it is a true bug in pristine-tar, it should be reported to pristine-tar and get fixed.
