i = i++ doesn't increment i. Why?

Possible Duplicates:
Why does this go into an infinite loop?

Things like i = i++ have undefined behavior in C and C++ because the value of a scalar object is changes twice within the same expression without intervening sequence point.

However I suppose that these kind of expressions have well-defined behavior in C# or Java because AFAIK the evaluation of argument goes left to right and there are sequence points all over.

That said, I'd expect i = i++ to be equivalent to i++. But it's not. The following program outputs 0.

using System;
class Program
{
    static void Main(string[] args)
    {
        int i = 0;
        i = i++;
        Console.WriteLine(i);
    }
}

Could you help me understand why?

Disclaimer: I am fully aware that whether or not the behavior of above-mentioned constructs is defined, they are silly, useless, unreadable, unnecessary and should not be used in code. I am just curious.