Hard links to directories: why not?

[Guy Harris]

>  Yes, before the rename system call existed, all mv's did basically
>the same thing as cp (but they deleted the original after successful
>writing of the copy).  However, when rename was created, many vendors
>(although not all, I'm sure) changed mv to use rename exclusively and
>to fail if the rename failed.

Pretty ****ing dumb of them, given that the BSD "mv" didn't do something
that silly, as I remember (4.3BSD's sure doesn't); if they got
"rename()" from 4.2BSD, one presumes they would have gotten a rational
"mv" from there as well.