Best way to use real upstream tag rather than upstream/ tarball import

I've been experimenting with the Salsa CI pipeline in a pure-git based workflow and I found that (at least in this example package where I'm using git-debrebase too) it fails, apparently because I don't have an upstream/1.2.3 tag.

I'm not importing any upstream tarballs into git. I want it to use the v1.2.3 tag instead.

I found that I could achieve this by prepending a prepare script to the build jobs, which runs git-deborig. That seems to satisfy whatever in the default pipeline is trying to make an orig with gbp. But surely that can't be the best way.

Can you advise?