update return values

setra_client/client.py

@@ -287,11 +287,13 @@ class SetraClient(object):
                              data=batchdata.json(),
                              headers=headers,
                              return_response=True)
-        if response.status_code in (409, 202):
+        if response.status_code in (204, 202):
             return 'OK'
+        elif response.status_code is 409:
+            return 'batch_found_but_cannot_be_updated'
         else:
             response.raise_for_status()
-            return response
+        return response
 
     def get_batch_complete(self, batch_id: str):
         """