Tuple!(size_t, size_t) rotateTail(R)(R whole, R right)
{
    if (whole.empty || right.empty || whole is right)
    {
        // Degenerate cases, just return all zeros
        return typeof(return).init;
    }
    auto w = whole.save, r = right.save;
    size_t rotated = 0;
    for (;; w.popFront, r.popFront, ++rotated)
    {
        if (r.empty)
        {
            assert(!w.empty && !right.empty);
            if (w is right) return tuple(2 * rotated, rotated);
            auto x = rotateTail(w, right);
            return tuple(rotated + x[0], rotated);
        }
        if (w is right)
        {
            assert(!w.empty && rotated);
            auto x = rotateTail(right, r);
            return tuple(rotated + x[0], x[0]);
        }
        assert(!w.empty);
        assert(!r.empty);
        swap(w.front, r.front);
    }
}