Your package rubygem-json failed to build from source in current rawhide. http://koji.fedoraproject.org/koji/taskinfo?taskID=7001957 For details on mass rebuild see https://fedoraproject.org/wiki/Fedora_21_Mass_Rebuild
Created attachment 906190 [details] build.log
Created attachment 906191 [details] root.log
Created attachment 906192 [details] state.log
Created attachment 912274 [details] Patch for rawhide