GitLab

Cube name might not be equal to the package name stripped by 'cubicweb-'.
For instance cubicweb-saem-ref cube name is "saem_ref", not saem-ref.

Use a python script to detect the cube name using pkg_resources.

Keep mirroring on hub.extranet.logilab.fr/cubicweb/cubicweb

Seems using a default value is broken here, see https://github.com/moby/moby/issues/15025#issuecomment-371799311

By using a build argument CW_INSTANCE_NAME. The build argument cannot be set to
CW_INSTANCE because when running "ENV CW_INSTANCE=$CW_INSTANCE" docker lookup
the environment first before build arguments.