Allow specific branches to be mirrored
Zendesk: https://gitlab.zendesk.com/agent/tickets/68186
It would be great to be able to choose one or more specific branches to be mirrored rather than the whole repository. This has many use-cases. In one example, a project fork could mirror only the master branch to keep their fork up to date. In the customer's case they're working with 3rd parties that are on GitHub. They would like to accept contributions on GitHub and have a particular branch mirrored to GitLab.