tr-link not wokring with need-parts

[danwos]

If need-parts are used, tr_link does not check, if a given id (containing a string like 'need_id.part_id`) fits the target option.

Used like:

.. test-file:: My Test Data
   :file: teen_car/test_run_1.xml
   :id: TESTFILE_1
   :auto_suites:
   :auto_cases:
   :links: [[tr_link('case_name', 'id_complete')]]

Where [[tr_link('case_name', 'id_complete')]] is the part which should make it work.
Using id instead of id_complete works.