In #566990 a forced dependency of libutempter was added to the ebuild. Upstream has since added a configure option. https://github.com/tmux/tmux/commit/75b2c1693e66d624ef0c012b3b811d08a42ba722 I would like to request that a USE flag be added on gentoo. Thank you
commit 47d41744d88f1bad4875341be6c9a95da6db665a Author: Lars Wendler <polynomial-c@gentoo.org> Date: Thu Jun 2 14:33:40 2016 app-misc/tmux: Bump to version 2.2 (bug #579620). Made utempter support optional (bug #584690). Package-Manager: portage-2.2.28 Signed-off-by: Lars Wendler <polynomial-c@gentoo.org>