basename -bash generates an error

[Brian Matheson]

Hi there,

I occasionally use basename $0 in scripts that I sometime source in my
interactive shell.  This construct seems to be broken now.  

Old behavior:
red:~$ basename $0
-bash

New behavior:
orange:~/lib/sh$ basename $0
basename: invalid option -- b
Try `basename --help' for more information.

Looks like a misbehavior in option parsing.

Randomly,
Brian