ES6 circular dependencies

I have the following files

```js
//test1.js
import {Test2} from 'test2';
export class Test1 {
constructor() {
console.log(new Test2());
}
}

//test2.js
import {Test1} from 'test1';
export class Test2 {
constructor() {
console.log(new Test1());
}
}

//main.js
import {Test1} from 'test1';
console.log(new Test1());
```

on compiling in Advanced mode I get this error:

> test2.js:1: ERROR - required "module$test1" namespace not provided yet
> import {Test1} from 'test1';

Is this a bug or am I doing something wrong? If I comment the import line in test2.js it compiles but not with the result I want:

```js
function a() {
console.log(new Test1); // !!!! who is Test1 ????
}
;console.log(new function() {
console.log(new a);
});
```