As far as I can tell, the src provided in a Galaxy requirements.yml must provide the role structure at its root in order for Galaxy to pull it in from a requirements file. It seems it would be useful to have the ability to provide a path to the role within the src. For example, I would like to have an ansible-role directory within the source for a project.
It looks like this would require a few lines to be added to https://github.com/ansible/ansible/blob/devel/lib/ansible/galaxy/role.py. If there is any interest in this, I will open a merge request.
Regards,
Matthew Williams