After I ask on irc: I get: dependency.bad 22 app-emulation/qemu/qemu-2.0.0-r1.ebuild: DEPEND: amd64(default/linux/amd64/13.0) ['sys-infiniband/librdmacm', '>=net-fs/libnfs-1.9.3', 'sys-infiniband/librdmacm[static-libs(+)]', '>=net-fs/libnfs-1.9.3[static-libs(+)]'] I'd suggest to stable mask the use, go ahead if you think is fine.
just file bugs for these packages to get them stabilized