https://bugzilla.redhat.com/show_bug.cgi?id=976468
--- Comment #4 from Vít Ondruch vondruch@redhat.com --- No, ruby(release) will never be backported. For F18 and older releases, we stay with ruby(abi). You should either maintain two versions of .spec file (that is preferred) or conditionalize the build.
BTW your %files section still contains:
%dir %{gem_instdir} %{gem_instdir}
Which is wrong. I would suggest to keep the %dir prefixed entry and fix the rest of issues, which it will cause.