Okay, while POSIX compatibility is a questionably desirable thing,
has anyone fixed cp to be compatible with namei()?

# cp netbsd /
overwrite /netbsd? y
cp: : No such file or directory
#

Maybe it's because my userland is behind my kernel, but this is a drag.
If you're going to fix namei() to ignore trailing slashes, great, but
at least make it not ignore the root directory!  (It appears to be more
cp's fault than namei()'s because I can cd to root (/) no problem.)