Monkey patch ES gem by re-opening module

The reason to do this instead of the prepend approach is that this
module is included in other places and as such prepending over that
method later seems to have no effect.

config/initializers/elastic_client_setup.rb

@@ -10,7 +10,6 @@ Gitlab.ee do
   ### Monkey patches
 
   Elasticsearch::Model::Response::Records.prepend GemExtensions::Elasticsearch::Model::Response::Records
-  Elasticsearch::Model::Response::Results.prepend GemExtensions::Elasticsearch::Model::Response::Results
   Elasticsearch::Model::Adapter::Multiple::Records.prepend GemExtensions::Elasticsearch::Model::Adapter::Multiple::Records
   Elasticsearch::Model::Indexing::InstanceMethods.prepend GemExtensions::Elasticsearch::Model::Indexing::InstanceMethods
   Elasticsearch::Model::Adapter::ActiveRecord::Importing.prepend GemExtensions::Elasticsearch::Model::Adapter::ActiveRecord::Importing
@@ -19,6 +18,32 @@ Gitlab.ee do
   Elasticsearch::Model::ClassMethods.prepend GemExtensions::Elasticsearch::Model::Client
   Elasticsearch::Model.singleton_class.prepend GemExtensions::Elasticsearch::Model::Client
 
+  # This monkey patch cannot be handled by prepend like the above since this
+  # module is included into other classes.
+  module Elasticsearch
+    module Model
+      module Response
+        module Base
+          if Gem::Version.new(Elasticsearch::Model::VERSION) >= Gem::Version.new('7.0.0')
+            raise "elasticsearch-model was upgraded, please remove this monkey patch in #{__FILE__}"
+          end
+
+          # Handle ES7 API where total is returned as an object. This
+          # change is taken from the V7 gem
+          # https://github.com/elastic/elasticsearch-rails/commit/9c40f630e1b549f0b7889fe33dcd826b485af6fc
+          # and can be removed when we upgrade the gem to V7
+          def total
+            if response.response['hits']['total'].respond_to?(:keys)
+              response.response['hits']['total']['value']
+            else
+              response.response['hits']['total']
+            end
+          end
+        end
+      end
+    end
+  end
+
   ### Modified from elasticsearch-model/lib/elasticsearch/model.rb
 
   [

ee/lib/gem_extensions/elasticsearch/model/response/results.rb

-# frozen_string_literal: true
-
-module GemExtensions
-  module Elasticsearch
-    module Model
-      module Response
-        module Results
-          # Handle ES7 API where total is returned as an object. This
-          # change is taken from the V7 gem
-          # https://github.com/elastic/elasticsearch-rails/commit/9c40f630e1b549f0b7889fe33dcd826b485af6fc
-          # and can be removed when we upgrade the gem to V7
-          def total
-            if response.response['hits']['total'].respond_to?(:keys)
-              response.response['hits']['total']['value']
-            else
-              response.response['hits']['total']
-            end
-          end
-        end
-      end
-    end
-  end
-end