Mono is not built in Fedora for sparc64 (current mono versions don't support it, as mentioned at http://mono-project.com/Supported_Platforms). As a consequence, all mono packages that don't use ExclusiveArch are going to end up getting an ExcludeArch: sparc64 added to them. Since the underlying problem is that mono is simply not available for that problem, it makes more sense to have the tracker bugs for all of those ExcludeArch issues block this bug rather than the main sparc64 tracker (Bug #531446).