junctions don't work with project.refs references

With ref-storage: project.refs, I get the following error, even though I used bst track and the ref is present in project.refs.

[00:00:02][][] FAILURE Fetching https://gitlab.com/freedesktop-sdk/freedesktop-sdk/
[00:00:02][][] FAILURE Loading pipeline
Error loading pipeline: git source at base/freedesktop-sdk-junction.bst [line 3 column 2]: expected ref 'None' was not found in git repository: 'https://gitlab.com/freedesktop-sdk/freedesktop-sdk/'

A workaround is to manually add the ref in the .bst file for the junction, but I really don't like that.

I've already mentioned it in #292 (comment 64566339) but I think this more important than the rest.