Importer fails to push when there's only one upload

[Robie Basak]

jtreg7 failed to push as follows:

Mar 23 12:19:41 juju-ad5025-prod-git-ubuntu-18 git-ubuntu[2109658]: 03/23/2023 12:19:41 - ERROR:Command exited 1: git push --atomic pkg "+refs/heads/importer/*:refs/heads/*" "refs/tags/importer/*:refs/tags/*" refs/notes/importer/changelog:refs/notes/commits refs/notes/importer/importer:refs/notes/importer
Mar 23 12:19:41 juju-ad5025-prod-git-ubuntu-18 git-ubuntu[2109658]: 03/23/2023 12:19:41 - ERROR:stdout:
Mar 23 12:19:41 juju-ad5025-prod-git-ubuntu-18 git-ubuntu[2109658]: 03/23/2023 12:19:41 - ERROR:stderr: error: src refspec refs/notes/importer/changelog does not match any
Mar 23 12:19:41 juju-ad5025-prod-git-ubuntu-18 git-ubuntu[2109658]: error: failed to push some refs to 'ssh://<email address hidden>/~git-ubuntu-import/ubuntu/+source/jtreg7'

I think this is because there was only one upload, and therefore no changelog notes.

[Robie Basak (racb)]

Note: this seems to work as a test. So something like that needs to be integrated into the importer's push call I think. I don't see any way of marking refspecs to be optional.

'refs/notes/importer/changelog' in r.references

[Robie Basak (racb)]

A thought on how to fix this: I could implement a git_push function which wraps the shell call, and allows for particular (partial) refspecs to be optional via its arguments. Then it could do the "x in r.references" test. The main push calls could use this function instead, and the function could be tested easily then.