I've some doubts on this commit: now when you add a layer, the "loader" is activated, but what will deactivate it?

Here is a small gist that shows my concerns: https://gist.github.com/yohanboniface/195a03ba352b69d873a2
Just adding this will add the "loader" ad vitam:
```
    L.featureGroup().addTo(map);
```
But maybe I've missed something.