Working with probabilistic atlas

I tried to use Brain_Data to load a mask based on DiFuMo atlas (https://parietal-inria.github.io/DiFuMo/)
Using the standard method (loading mask with Brain_Data and using expand_mask) doesn't work.
When looking at the loaded atlas, I find that it is already loaded as expanded. But then, trying to use roi_to_brain doesn't work as well.

```
a = nilearn.datasets.fetch_atlas_difumo(dimension=256)
mask = Brain_Data(a.maps)
```