Why does the compiler complain for ambiguity in overloaded function?

Question

In the following example everything compiles correctly and the function "void foo(int&)" is called.

void foo(const int&) { /* implementation */ };
void foo(int&) { /* implementation */ };

int main(int argc, char** argv)
{
    int i = 0;

    foo(i);
    return (0);
}

It's my understanding that the second function is called because both functions are an exact match but only the first one is a identity conversion and that's why it is a better match than the second function which is a qualification conversion.

void foo(const int&) { /* implementation */ };
void foo(int) { /* implementation */ };

int main(int argc, char** argv)
{
    int i = 0;

    foo(i);
    return (0);
}

But why does the compiler complain for ambiguity in this example? As i take it, the compiler should call "void foo(int)" because both functions remain an exact match but the first function is a identity conversion and the second function also remains a qualification conversion.