Your package rubygem-mysql2 failed to build from source in current F28. https://koji.fedoraproject.org/koji/taskinfo?taskID=24891156 For details on mass rebuild see https://fedoraproject.org/wiki/Fedora_28_Mass_Rebuild
A build was successfull: rubygem-mysql2-0.4.10-3.fc28 [1]. No update was found in bodhi. Closing the bug nonetheless. [1] https://koji.fedoraproject.org/koji/buildinfo?buildID=1019530