NULL SID not really useful, we better print "S-1-5-18"
Created attachment 15241 [details] patch for 4.9 and 4.10 cherry-picked from master
Assigning to Karolin for inclusion in the next releases.
(In reply to Andrew Bartlett from comment #2) Pushed to autobuild-v4-{9,10}-test.
(In reply to Karolin Seeger from comment #3) Pushed to both branches. Closing out bug report. Thanks!