feat: gitlab - ensure lastpipeline ref is the same as head branch

[rhariady]

what

This MR will change the behaviour of GitlabClient UpdateStatus to use previous lastPipeline only if it has a same Ref (branch).

why

This is to fix #5228 where a commit is referenced as head of two different branch (in case someone duplicate a branch and create separate MR)

tests

• I have tested my changes by returning commit status with lastpipeline of different Ref

references

[X-Guardian]

Hi @rhariady, I don't think this is going to totally fix the issue, as if the ref does not match, it is going to retry then fall back to using pull.Headbranch as the reference for the commit status. This may not choose the right pipeline if for example there are both GitLab and External pipelines running on an MR.

I think this can be resolved by adding some more code when the ref does not match to then use the list-the-status-of-a-commit API to find the correct status to update.

[rhariady]

Hi @X-Guardian! I have pushed another commit that implement your suggestion, but instead of calling list-the-status-of-a-commit only when the ref doesn't match, I end up using it to replace call to get-a-single-commit API in the first place.

I think it will be more effective, because we will have 1 less API call for every retry (in case there are another pipeline running). Also, i think list-the-status-of-a-commit is more aligned with the subsequent call, which is to set-the-status-of-a-commit.