`namespace_options` helper doesn't take implicit subgroup permissions into account
When a user is an owner or master on a top-level group, they are also implicit owners/masters of subgroups and projects. However, the
namespace_options helper and specifically the line at https://gitlab.com/gitlab-org/gitlab-ce/blob/master/app/helpers/namespaces_helper.rb#L7 only take into account explicit owned and master groups. A workaround is to explicitly add the user as an owner of the subgroup.
namespace_options is used in several locations, including when creating a new project and importing a project from another provider. With this bug present, the users cannot select the subgroups.