Your package qjson failed to build from source in current rawhide. http://koji.fedoraproject.org/koji/taskinfo?taskID=12863833 For details on mass rebuild see https://fedoraproject.org/wiki/Fedora_24_Mass_Rebuild
Created attachment 1125956 [details] build.log
Created attachment 1125957 [details] root.log
Created attachment 1125958 [details] state.log
%changelog * Sun Feb 14 2016 Rex Dieter <rdieter> 0.8.1-16 - %%check: make tests non-fatal xvfb-run isn't working "cannot connect to X server" (#1307965)
Hmm, does xvfb-run set $DISPLAY properly? For instance, trojita.spec can not use xvfb-run. It may need a direct call to Xvfb with a parameter for $DISPLAY, see http://pkgs.fedoraproject.org/cgit/rpms/trojita.git/commit/?id=8a5cc9e0425bbfa9be7edfb9c27cdffaba070aaf
xvfb-run -a is supposed to automatically find (and use) a free DISPLAY In short, you're working around the fact that xvfb-run doesn't run properly either. I guess I should file a bug
Heh, turns out that on my rebuild to make the check non-fatal, the xvfb-run -a call ran properly (without error)