preserving index after merging ancillary fields to atl06 dataframe

Author: jpswinski

sliderule/icesat2.py

@@ -791,7 +791,7 @@ def atl06p(parm, asset=DEFAULT_ASSET, version=DEFAULT_ICESAT2_SDP_VERSION, callb
         tstart_merge = time.perf_counter()
         for field in field_dictionary:
             df = geopandas.pd.DataFrame(field_dictionary[field])
-            gdf = gdf.merge(df, on='extent_id', how='inner')
+            gdf = gdf.merge(df, on='extent_id', how='inner').set_axis(gdf.index)
         profiles["merge"] = time.perf_counter() - tstart_merge
 
         # Return Response