Yes, Python closes over references to a mutable variable, and list comprehensions work the same way. It doesn't close over the value.

I'd make the suggestion that closures are not very "Pythonic". Use objects instead:

    class add_n_func:
        def __init__(self, n):
            self.n = n
        def __call__(self, x):
            return x+self.n

    return [add_n_func(n) for n in range(10)]