debdiff: wrong previous version when package from bullseye-security is newer than bullseye

Describe the bug

Checking the debdiff (source and binary) for gdk-pixbuf upload-to-bullseye-security work request, it gets the wrong version in the archive to compare the newer version. It's using 2.42.2+dfsg-1+deb11u2 which is in the bullseye archive, but 2.42.2+dfsg-1+deb11u3 is the newer one in the bullseye-security one.

How to reproduce the bug

Upload a package that has different versions in bullseye and bullseye-security.

Operating system

Debian 13 trixie

Versions of debusine and its dependencies

debusine.debian.net is 0.12.3.dev89+g554e08ca