The new version of sys-apps/paludis fails to build with MAKEOPTS="-jX", X>1. This issue is already known and fixed upstream, see http://git.exherbo.org/paludis/paludis.git/commit/?id=1bbd4440fe4fb82a9ebd61d3f17b9ffa259eb17f Please add the corresponding patch to the repository, or bump the version to the latest commit immediately (AFAICS this would also allow building paludis with Ruby 2.4).
commit 198647136c733425f74386ebb6682113791a9357 Author: Michał Górny <mgorny@gentoo.org> AuthorDate: Tue Feb 21 18:25:59 2017 Commit: Michał Górny <mgorny@gentoo.org> CommitDate: Tue Feb 21 18:26:25 2017 sys-apps/paludis: Snapshot bump, #610354