pw/pwupd.h has.. int editgroups(char *name, char **groups); but it's never declared let alone used.
A commit references this bug: Author: bapt Date: Fri May 29 10:07:21 UTC 2015 New revision: 283695 URL: https://svnweb.freebsd.org/changeset/base/283695 Log: Remove dead declaration PR: 195928 MFC after: 2 days Changes: head/usr.sbin/pw/pwupd.h
A commit references this bug: Author: bapt Date: Sun May 31 00:52:46 UTC 2015 New revision: 283796 URL: https://svnweb.freebsd.org/changeset/base/283796 Log: MFC: r283695 Remove dead declaration PR: 195928 Changes: _U stable/10/ stable/10/usr.sbin/pw/pwupd.h