Variables not evaluated before comparison with the list of allowed services

Summary

The variables $CI_REGISTRY_IMAGE and $CI_COMMIT_REF_NAME are apparently not evaluated before comparison with the list of allowed services.

Steps to reproduce

Allow the project as registry service in the runner Docker configuration:

allowed_services = ["docker:*", "registry.example.com/example/project:*"]

Build the project which uses the service
see the Job log

Actual behavior

ERROR: The $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_NAME is not present on list of allowed services

Expected behavior

The $CI_REGISTRY_IMAGE and $CI_COMMIT_REF_NAME variables are evaluated before the comparison with the list of allowed services. In the example above, CI_REGISTRY_IMAGE:CI_COMMIT_REF_NAME could be evaluated to registry.example.com/example/project:latest, which would pass the configured allowed_services setting.

This worked with gitlab-ci-multi-runner 9.3.0. Maybe the changes of !596 (merged) cause the issue?

Relevant logs and/or screenshots

ERROR: The $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_NAME is not present on list of allowed services
- docker:*
- registry.example.com/example/project:*

Environment description

docker:17.06.0-ce

Used GitLab Runner version

Running with gitlab-ci-multi-runner 9.4.1 (d24b11c)