When I use MMA to solve this integral

```
Integrate((1 - Cos(x))/( 2 - Cos(x) - Cos(y)), {x, -Pi, Pi}, {y, -Pi, Pi})
```

it returns `8I*Pi*Log(2)`

, which is obviously wrong.

If I iteratedly calculate it

```
Integrate(Integrate((1 - Cos(x))/(2 - Cos(x) - Cos(y)), {y, -Pi, Pi}), {x, -Pi, Pi})
```

MMA gives `2Pi^2`

, which is correct.

Can anybody give an explaination?