Need a way to run pipelines without manifests to test release tarballs after tagging
In Cerbero, when we're tagging for a new gstreamer release, we set a special variable in
recipes/custom.py which tells Cerbero to use tarballs instead of git. The purpose is four-fold: (1) Test the tarballs on all platforms (2) Speed up user builds because tarballs are smaller than git tags (3) Reduce potential strain on our git infrastructure (4) Make it easier for third-party CIs to cache sources.
However, we can't use this code in our CI because it breaks our usage of git manifests to build specific commits. So, since cerbero!123 (merged) we can't test the tarballs on the CI at all.
We need a way to tell the CI that with this pipeline, it should not use git manifests since we're testing tarballs for all gstreamer repos, and then not pass the manifests to cerbero at all.