Cross project change id
There are situations where the same change should be merged into multiple branches (gitlab-ce#33141 (closed)) but the branches may not be in the same project. For example, I may have 5 forks for a common project, and each fork is customer specific. I want to be able to merge the same change into all 5 forks and have a unified id to track the change.
Perhaps we can extend group merge requests #3427 (closed) to not handle merging 5 related changes into their respective project, but also allowing a single change to be merged to 5 different projects.
Links / references
Gerrit has a change id system which allows a single change to be cherry picked and merged into different branches and projects, and provides and id that connects all the changes.