As written in the topic, app-arch/xz-utils should use build_binaries() function instead of multilib_is_native_abi() function to conditionally build binaries.
should be multilib_build_binaries instead of build_binaries
should be all set now in the tree; thanks for the report! Commit message: Use multilib_build_binaries to build binaries http://sources.gentoo.org/app-arch/xz-utils/xz-utils-5.0.5-r1.ebuild?r1=1.12&r2=1.13 http://sources.gentoo.org/app-arch/xz-utils/xz-utils-5.1.3_alpha.ebuild?r1=1.1&r2=1.2 http://sources.gentoo.org/app-arch/xz-utils/xz-utils-9999.ebuild?r1=1.17&r2=1.18