Fedora 18 changes the way how to work with services in spec files. It introduces new macros - %systemd_post, %systemd_preun and %systemd_postun; which replace scriptlets from Fedora 17 and older (see https://fedoraproject.org/wiki/Packaging:ScriptletSnippets#Systemd, https://bugzilla.redhat.com/show_bug.cgi?id=850016).
I have made the changes locally. Will push when there is a new release, probably only for Rawhide.
This was mistakenly pushed for Fedora 17, which doesn’t support the new macros (bug 947627).