anti-shellshock suggestions

[Lee Bast]

> Has been working sofar (on a formerly vulnerable OS X 10.6.8 with bash 3.2.x) but I'm a bit anxious to see if the machine will still boot.
> I have no idea if there's a checksum on /bin/bash in 10.6+ or 10.7+ .
	I've seen no issues so far with replacing bash & sh on any system, including some VM testing (though I haven't tested under Yosemite, not that that should be in production). /bin/sh appears to basically be bash compiled with POSIX mode as default and maybe somewhat modified startup behavior, but while MacPorts doesn't offer that option bash, when invoked as sh, should automatically enter POSIX mode at least anyway.
	While of course all the normal advice applies (backups, testing on spare system or in a VM etc) I'd be surprised if it wasn't a drop-in replacement. Bash 4 introduced some new features (limited associative arrays, new builtins and extra ops for some old ones, more options for brace expansion etc) and bug fixes but while scripts written for Bash 4 could fail under Bash 3 I haven't seen much that would cause the reverse. At any rate, it should be trivial to swap back if you needed to.