赤塚ギャグの「忘れようにも思い出せない」じゃないけど、放置しようにも {group,gshadow,passwd,shadow}.newが /etcに存在しない。
ドユコト?

http://mirrors.slackware.com/slackware/slackware64-current/ChangeLog.txt
> Sun Feb 25 19:16:52 UTC 2024
> a/etc-15.1-x86_64-7.txz: Rebuilt.
> Don't leave {group,gshadow,passwd,shadow}.new laying around.
> We'd left these as a reference in case new default entries were added so that
> the admin could take a look at them and merge the new entries into the
> existing files. But we've been merging them over automatically for quite some
> time. The files contain no unique information and are sort of a footbullet.