Log Message:
Update to 6.39

Upstream changes:
6.39      2019-05-06 14:18:39Z
    - Document current best practices (GH#314) (Olaf Alders)
    - Document order in which handlers fire (GH#315) (Olaf Alders)
    - SKIP nntp test for now (GH#317) (Olaf Alders)