Customize default merge request titles

In previous versions of GitLab, the default title for a new merge request came from the source branch or first commit, and you couldn't enforce a consistent naming convention across your project.

Now you can configure a default merge request title template per project. Templates support variables for the source branch, target branch, first commit subject, linked issue ID, issue title, and a human-readable version of the source branch name. For example, the template Resolve %{issue_id} "%{issue_title}" produces titles like Resolve 123 "Fix login bug". You can still edit the title before creating the merge request.