[_606] attach server response message to exception

Includes test with atomic_metadata.
Other APIs that could use this feature include:
  replica_truncate

Author: d-w-moore

irods/connection.py

@@ -149,7 +149,9 @@ def recv(self, into_buffer = None
             except TypeError:
                 err_msg = None
             if nominal_code(msg.int_info) not in acceptable_codes:
-                raise get_exception_by_code(msg.int_info, err_msg)
+                exc = get_exception_by_code(msg.int_info, err_msg)
+                exc.server_msg = msg
+                raise exc
         return msg
 
     def recv_into(self, buffer, **options):

irods/test/meta_test.py

@@ -121,6 +121,18 @@ def tearDown(self):
 
     from irods.test.helpers import create_simple_resc_hierarchy
 
+    def test_atomic_metadata_json_error__issue_606(self):
+        path = self.coll_path + "/atomic_meta_issue_606"
+        obj = self.sess.data_objects.create(path)
+        obj.unlink(force = True)
+        try:
+            obj.metadata.apply_atomic_operations(AVUOperation(operation="add", avu=iRODSMeta('a','b','c')))
+        except Exception as e:
+            resp = e.server_msg.get_json_encoded_struct()
+            self.assertIn(
+                'Entity does not exist [entity_name={}]'.format(obj.path),
+                resp['error_message'])
+
     def test_atomic_metadata_operations_244(self):
         user = self.sess.users.get("rods")
         group = self.sess.groups.get("public")