why () is () and [] is [] work in other way?

[dmitrey]

I have spent some time searching for a bug in my code, it was due to
different work of "is" with () and []:
>>> () is ()
True
>>> [] is []
False

(Python 2.7.2+ (default, Oct  4 2011, 20:03:08)
[GCC 4.6.1] )

Is this what it should be or maybe yielding unified result is better?
D.