Simplify `branch_name` in bin/changelog
The --short option has existed since at least 1.8.1:
https://git-scm.com/docs/git-symbolic-ref/1.8.1
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
The --short option has existed since at least 1.8.1:
https://git-scm.com/docs/git-symbolic-ref/1.8.1