gitlab-rake gitlab:setup does not import value of initial_shared_runners_registration_token

In the gitlab.rb you can define the value of gitlab_rails['initial_shared_runners_registration_token']. This work flawlessly for a local database. Unfortunately, when you setup an external database, you have to use gitlab-rake gitlab:setup, but the value is ignored.

I couldn't find any documentation for an environment variable that could be use to set this value (like you have available for the root password GITLAB_ROOT_PASSWORD).

Can you let me know if I missed something of if I can submit a PR to support a new environment variable?

Thanks.