Bug in needflow with root-id and parent_needs

[danwos]

Using needflow with root_id does not take links from nested needs into account, or more specifically the automatically set link type parent_needs is not shown and can not be configured to be shown.

Example

.. req:: My Requirement
   :id: REQ_001

   .. spec:: My nested Specification
      :id: SPEC_001

In this example SPEC_001 will get parent_needs set to REQ_001.
The related parents_needs_back is also set for REQ_001toSPEC_001`.

When using now:

 .. needflow::
    :root_id: REQ_001
    :root_depth: 2

SPEC_001 is not shown in the diagram.
Also setting :link_types: parent_needs does not help.

Is my configuration somehow wrong or is parent_needs currently ignored?