Probably a GNU thing. Yeah, okay, it's a sloppy command but the trailing
slash was added by TAB (complete) and I'm fairly sure that basename
shouldn't dump core whatever.
# ls daemontools/
./ envuidgid.html multilog.html softlimit.html svok.html
../ fghack.html setlock.html supervise.html svscan.html
envdir.html install.html setuidgid.html svc.html tai64n.html
# ls /usr/share/doc/daemontools-0.53/
./ ../ BLURB CHANGES INSTALL README README.rpm THANKS TODO VERSION
# mv daemontools/ /usr/share/doc/daemontools-0.53/html
mv: basename.c:67: base_name: Assertion `all_slashes || *(p - 1) != '/''
Aborted (core dumped)
Dunno, what sh-utils package you are using, as the assertion that you are seeing
is not in any sh-utils-2.0-11 sources.