I just updated to python 3.6. And i see this in my output for several packages. [ebuild R ] x11-proto/xcb-proto-1.12-r2 PYTHON_TARGETS="-python3_4*"
commit 82d05e71548cd76032cfb366e8727106ad88ff3e Author: Manuel Rüger <mrueg@gentoo.org> Date: Thu May 4 17:42:22 2017 +0200 x11-proto/xcb-proto: Add python3_6 Package-Manager: Portage-2.3.5, Repoman-2.3.2