Migrate Repository#local_branches from gitlab-ee.
REF: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/249
This will help us to avoid posible merge conflicts when merging gitlab-ce to gitlab-ee
REF: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/249
This will help us to avoid posible merge conflicts when merging gitlab-ce to gitlab-ee