[Python] Dictionary creation with fromkeys and mutable objects. A surprise [duplicate]

I came across this behavior that surprised me in Python 2.6 and 3.2:

>>> xs = dict.fromkeys(range(2), [])
>>> xs
{0: [], 1: []}
>>> xs[0].append(1)
>>> xs
{0: [1], 1: [1]}


However, dict comprehensions in 3.2 show a more polite demeanor:

>>> xs = {i:[] for i in range(2)}
>>> xs
{0: [], 1: []}
>>> xs[0].append(1)
>>> xs
{0: [1], 1: []}
>>>


Why does fromkeys behave like that?

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