Comment 5 for bug 791221

I think this one is even simpler to illustrate the change:

class Foo:
    def __dir__(self):
        return ['a', 'b', 'c']

class Bar:
    def __dir__(self):
        return ('a', 'b', 'c')

print dir(Foo())
print dir(Bar())

AFAICT, in Python 2.7.1 you get two lines of ['a', 'b', 'c'] while in 2.7.2rc2, the second line gives you the TypeError.