Your package ginac failed to build from source in current rawhide. https://koji.fedoraproject.org/koji/taskinfo?taskID=17716964 For details on mass rebuild see https://fedoraproject.org/wiki/Fedora_26_Mass_Rebuild
Created attachment 1252212 [details] build.log
Created attachment 1252213 [details] root.log
Created attachment 1252214 [details] state.log
I think this is due to a test that sometimes fails and sometimes passes. Koschei also reports build failures quite frequently.
zbyszek's ginac-1.7.2-3.fc26 completed http://koji.fedoraproject.org/koji/buildinfo?buildID=843482
It seems that the last gcc update helped.