rename strangeness, a possible bug

[Guy Harris]

>One of them is what happens when you move a directory to a
>sub-directory of itself.  Consider the following:
>
>	directory structure:	/a/dir1/dir2/dir3/dir4/dir5
>
>		command:	mv /a/dir1 /a/dir1/dir2
>
>		command:	(in /a/dir1/dir2) mv .. dir3k

	Script started on Sat Aug 26 15:38:07 1989
	auspex% cat /etc/motd
	SunOS Release 4.0 (AUSPEX) #1: Thu Jun 1 06:56:44 PDT 1989
	auspex% mv /tmp/dir1 /tmp/dir1/dir2
	mv: /tmp/dir1: rename: Invalid argument
	auspex% cd /tmp/dir1/dir2
	auspex% mv .. dir3k
	mv: ..: rename: Invalid argument
	auspex% ^D
	script done on Sat Aug 26 15:38:22 1989

SunOS and, I think, other systems that have picked "rename" up from
4.xBSD, won't let you do such a move.  They will let you do other "safe"
moves, though.