error while unmarshalling stacker file (binds field)

If I add a binds field in stacker file like this 

``` 
binds:
        - Source: test 
          Dest: test
```

I get this error 

```error: unknown run array type: map[interface {}]interface {}``` 


but if I use binds field like this it works fine

``` 
binds:
        - test -> test 
```