The resason is that { ENCODINGSDIR=$RPM_BUILD_ROOT%{_datadir}/X11/fonts/encodings pushd "${ENCODINGSDIR}" &> /dev/null mkfontscale -n -e "${ENCODINGSDIR}" -e "${ENCODINGSDIR}/large" popd &> /dev/null } ends up leaving RPM_BUILD_ROOT in the encodings.dir files
Fixed in 7.2-3, I think.