Use a copy of dask_gufunc_kwargs (#4402)
Use a copy of dask_gufunc_kwargs (#4402)

* Use a copy of dask_gufunc_kwargs

* Move copy inside else statement
jhamman/xarray,pydata/xarray,pydata/xarray,jhamman/xarray,markelg/xray,jhamman/xarray,pydata/xarray,markelg/xray,markelg/xray