After upgrading to kde-apps/konsole-16.12.3, --new-tab option (that I use for years) doesn't work anymore. It just opens a new window.
see to be known https://bugs.kde.org/show_bug.cgi?id=373440#c12
Thanks, backported in -r1. https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=253b68324cf4294d02524720a440f2cf14a085c5