I ran pwck and it dumped core.
Created attachment 500624 [details] emerge --info
Created attachment 500626 [details] gdb's stack trace
The bug has been referenced in the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=ec0a8306f712c40b6b84d721b4ed70d9f4703e8b commit ec0a8306f712c40b6b84d721b4ed70d9f4703e8b Author: Lars Wendler <polynomial-c@gentoo.org> AuthorDate: 2018-04-30 16:02:31 +0000 Commit: Lars Wendler <polynomial-c@gentoo.org> CommitDate: 2018-04-30 16:05:03 +0000 sys-apps/shadow: Security bump to version 4.6 Bug: https://bugs.gentoo.org/647790 Bug: https://bugs.gentoo.org/635750 Package-Manager: Portage-2.3.31, Repoman-2.3.9 sys-apps/shadow/Manifest | 1 + sys-apps/shadow/shadow-4.6.ebuild | 211 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 212 insertions(+)}
Can you plese verify and report back if this still happens with sys-apps/shadow-4.6 version?
Intermittent, happened a long time ago, no longer reproducible.