Your package rubygem-rack-mount failed to build from source in current rawhide. http://koji.fedoraproject.org/koji/taskinfo?taskID=7003502 For details on mass rebuild see https://fedoraproject.org/wiki/Fedora_21_Mass_Rebuild
Created attachment 906338 [details] build.log
Created attachment 906339 [details] root.log
Created attachment 906340 [details] state.log