https://bugzilla.redhat.com/show_bug.cgi?id=1083941
--- Comment #38 from Han Frederic han@math.jussieu.fr --- Thank you! If it helps here is a current update.
http://webusers.imj-prg.fr/~frederic.han/fedora/SPECS/giac.spec
http://webusers.imj-prg.fr/~frederic.han/fedora/SRPMS/giac-1.2.2-1.fc22.src....
The testsuite is very sentitive and needed a small patch. (I took the one I have done for the sage spkg)
I have done something with the upstream naming scheme (1.2.2-43) but you may find a better solution...