Created attachment 452754 [details] DateTime-Calendar-Julian-0.04.ebuild DateTime::Calendar::Julian is apparently a dependency of biber-2.6 (see e.g. https://github.com/plk/biber/commit/6ca10da89f51578c48453521e46e26e485e1a952). I have attached my attempt at DateTime-Calendar-Julian-0.04.ebuild, which seems to work on my x86-64 box.
Added. Thanks. commit b85c6b3b9f4af928092ace19197347bd65f682b3 Author: Kent Fredric <kentnl@gentoo.org> Date: Wed Nov 9 11:47:57 2016 +1300 dev-perl/DateTime-Calendar-Julian: Add to tree at 0.40.0 re bug #599236 Requested by "MW" for a future release of dev-tex/biber