std.algorithm.remove using SwapStrategy.unstable doesn't works

[Aleksandar Ružičić]

I'm trying to use remove() from std.algorithm to remove item from an
array and when I tried to use SwapStrategy.unstable (as I don't need
to maintain order of items in array and I want to optimize where ever
I can) I came to surprising results. In the example below one would
expect that item at index 2 (number 3 in example) will be removed but
instead item at index 0 is removed from array.

Is this a bug or I'm missing a point?

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import std.stdio, std.algorithm;

void main(string[] args) {

        auto a = [1,2,3,4];

        foreach (e; a) writef("%s ", e); writefln("(%s)", a.length); // 1 2 3 4 
(4)

        auto i = a.indexOf(3);

        writefln("%s", i);      // 2

        if (i > -1) {
                a = remove!(SwapStrategy.unstable)(a, i);
        }

        foreach (e; a) writef("%s ", e); writefln("(%s)", a.length); // 4 2 3 
(3) !?!
}

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thx in advance,
Aleksandar