In my scenario, the branch job is a test-run job. The job is triggered when a feature branch is pushed to GitLab. It then attempts a merge into the integration branch (in this case master) to check if it would merge cleanly if the merge request was accepted.
So this job is a pre-check to tell the feature branch developer that his work won't integrate cleanly, without having to get the reviewer involved yet.
Only when this branch job passes, can the developer create a merge request and submit it for code review. This allow for less time wasted on the reviewers.
The reviewer, once happy, merges the branch to master, and deletes the feature branch. This triggers the build job.
At this stage, when the branch job is triggered again, it fails because the feature branch no longer exists. So indeed, I would have liked to have this behaviour as an option, not as a default. The way it works now is very implicit and not very obvious. It would be better to be able to configure this behaviour.
I am not using any of the 1.4.0 features specifically, I was upgrading to stay up to date.
So if this doesn't get patched or added to the next release, I will be stuck to the 1.3 release forever, which might be an issue in the future.
So yes, if you could add it as soon as you can, it would be greatly appreciated.
Thanks for your help with this.