Fix version check of netCDF4
Fix version check of netCDF4

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