Fix 'to_masked_array' computing dask arrays twice (#3006)
Fix 'to_masked_array' computing dask arrays twice (#3006)


xray/xray,markelg/xray,shoyer/xray,jhamman/xarray,jhamman/xarray,pydata/xarray,markelg/xray,markelg/xray,shoyer/xarray,shoyer/xarray,pydata/xarray,pydata/xarray,jhamman/xray,jhamman/xarray