dev-texlive/texlive-langczechslovak-2016 needs for successfull "compilation" luatex85.sty which is only provided by dev-texlive/texlive-luatex. Therefore, a corresponding DEPEND is needed. (Probably an RDEPEND is not needed.)
commit 75226ee3a6b10a254656dc58292c2518bfa5a5ad Author: Alexis Ballier <aballier@gentoo.org> Date: Sun Jan 22 21:23:36 2017 +0100 dev-texlive/texlive-langczechslovak: add dep on tl-luatex, bug #606802 Package-Manager: Portage-2.3.3, Repoman-2.3.1 thanks!