Comment 1 for bug 1728690

I think the whole thing is safe to remove. The only logic that is not test or config that I can find is this which is called when creating a role:

        if role['name'] == CONF.member_role_name:
            # Use the configured member role ID when creating the configured
            # member role name. This avoids the potential of creating a
            # "member" role with an unexpected ID.
            role['id'] = CONF.member_role_id
        else:
            role = self._assign_unique_id(role)

In core, there is add_user_to_project( which was the v2 implementation. That called ensure_default_role() to make sure the role existed. This whole path should be V2 onlymy and can be removed.