From Fedora Project Wiki

The current Complex Font Template leaves an unexpanded macro in SRPMS. We propose to take two actions to fix the issue:

Move the macro

 %_font_pkg -n <FAMILY> -f %{fontconf}-<FAMILY>.conf <NAME>*.ttf

Currently is right after the %description which is what causes issues. Moving it after the %clean section matches with the Simple Fonts Template, is where the expansion of the macro would normally live, and fixes the problem.

This will resolve the problem in new packages.

Add a Dummy Macro

Add a "dummy" %_font_pkg macro to redhat-rpm-config which checks to see if it is set, and if not, evaluates to %{nil}. As suggested by Panu

This would mean that existing packages would no longer have the issue and would be effectively "grandfathered".