As it breaks on the boost version change.
commit 3a99f331a3db0acb7fa15f2b6785392695a5e0f8 Author: Anthony G. Basile <blueness@gentoo.org> Date: Fri Aug 14 08:34:04 2015 -0400 sys-fs/encfs: add slot equals matching for boost and openssl Gentoo-Bug: 557414