SRPM Buildtime macros

All macros in Summary: and %description need to be expandable at srpm buildtime. Because SRPMs are built without the package's BuildRequires installed, depending on macros defined outside of the spec file can easily lead to the unexpanded macros showing up in the built SRPM. One way to check is to create a minimal chroot and build the srpm:

mock --init
mock --copyin [SRPM] /
mock --shell bash
rpm -ivh [SRPM]
cd /builddir/build/SPECS
rpmbuild -bs --nodeps [SRPM]
rpm -qpiv /builddir/build/SRPMS/[SRPM]

Check the rpm output for unexpanded macros (%{foo}) or missing information (when%{?foo} is expanded to the empty string). Even easier is to simply avoid macros in Summary: and %description unless they are defined in the current spec file.