Gets only the last values when section in gitconfig is duplicated

For some reason, in my `.gitconfig` I have the `[user]` section duplicated (on windows).

So it looks like this:

```
[user]
name = Zoltan Kochan
[user]
email = zoltan@xxx.xxx
```

git-config returns a config with a user property that contains only the email:

``` js
{
user: {
email: 'zoltan@xxx.xxx'
}
}
```