Fix to guarantee lazy loading of data
Fix to guarantee lazy loading of data

jhamman/xarray,clarkfitzg/xray,markelg/xray,kjordahl/xray,cpaulik/xray,shoyer/xarray,hetland/xray,jhamman/xarray,pydata/xarray,rabernat/xray,shoyer/xarray,rabernat/xray,petercable/xray,hetland/xray,cpaulik/xray,shoyer/xray,pydata/xarray,markelg/xray,kjordahl/xray,drewokane/xray,chunweiyuan/xarray,markelg/xray,clarkfitzg/xray,pydata/xarray,jcmgray/xarray,xray/xray,jhamman/xray,NicWayand/xray,jhamman/xarray