Aliases for services docker images

We're really enjoying using GitLab CI with the container registry feature. However, we are struggling to use the "services" feature with our internally-defined docker images (from the GitLab container registry and another registry).

We need to be able to use services where the image names are long and complicated, e.g.:

job:
    image: git.example.com:9999/group/project-a:latest
    services:
        - other-registry.example.com:9999/group/project-b:1.0
        - git.example.com:9999/group-b/project-c:develop

It would really help if we could specify network aliases for each of these services (docker-compose allows something like this) e.g.:

job:
    image: git.example.com:9999/group/project-a:latest
    services:
        - backend:git.example.com:9999/group/project-b:1.0
        - db:git.example.com:9999/group-b/project-c:develop
    script:
        - curl http://backend
        - curl http://db