sys-apps/baselayout compile failed

 * Package:    sys-apps/baselayout-2.7
 * Repository: gentoo
 * Maintainer: williamh@gentoo.org base-system@gentoo.org
 * USE:        abi_x86_64 amd64 elibc_glibc kernel_linux split-usr userland_GNU
 * FEATURES:   network-sandbox preserve-libs userpriv usersandbox
 * Converting /lib from a dir to a symlink
 * ERROR: sys-apps/baselayout-2.7::gentoo failed (setup phase):
 *   non-empty dir found where we needed a symlink: /lib
 * 
 * Call stack:
 *               ebuild.sh, line 125:  Called pkg_setup
 *   baselayout-2.7.ebuild, line  23:  Called multilib_layout
 *   baselayout-2.7.ebuild, line 108:  Called die
 * The specific snippet of code:
 *                                      die "non-empty dir found where we needed a symlink: ${prefix}lib"
 * 
 * If you need support, post the output of `emerge --info '=sys-apps/baselayout-2.7::gentoo'`,
 * the complete build log and the output of `emerge -pqv '=sys-apps/baselayout-2.7::gentoo'`.
 * The complete build log is located at '/var/tmp/portage/sys-apps/baselayout-2.7/temp/build.log'.
 * The ebuild environment file is located at '/var/tmp/portage/sys-apps/baselayout-2.7/temp/die.env'.
 * Working directory: '/var/tmp/portage/sys-apps/baselayout-2.7/homedir'
 * S: '/var/tmp/portage/sys-apps/baselayout-2.7/work/baselayout-2.7'

Converting /lib from a dir to a symlinkということなので， /etc/portage/make.confに以下を追記したところ無事通りました．

SYMLINK_LIB=no