add fix for parallel regridder merge error with xarray (#332)

* add fix for parallel regridder merge error with xarray

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

xesmf/frontend.py

@@ -1030,6 +1030,10 @@ def _init_para_regrid(self, ds_in, ds_out, kwargs):
             )
             out_chunks = [ds_out.chunks.get(k) for k in ['y_out', 'x_out']]
 
+        # Rename coords to avoid issues in xr.map_blocks
+        for coord in list(self.out_coords.keys()):
+            ds_out = ds_out.rename({coord: coord + '_out'})
+
         weights_dims = ('y_out', 'x_out', 'y_in', 'x_in')
         templ = sps.zeros((self.shape_out + self.shape_in))
         w_templ = xr.DataArray(templ, dims=weights_dims).chunk(