This bug tracks the implementation of the EAPI 3 feature mentioned in the summary.
This is in svn r13390.
(In reply to comment #1) > This is in svn r13390. Via gitweb: http://git.overlays.gentoo.org/gitweb/?p=proj/portage.git;a=commit;h=0f7b2df6fbe0685c3189f0c62ce92c845dbee7e2