Send lockVersion from MR description task list

app/assets/javascripts/merge_request.js

@@ -35,6 +35,7 @@ function MergeRequest(opts) {
       dataType: 'merge_request',
       fieldName: 'description',
       selector: '.detail-page-description',
+      lockVersion: this.$el.data('lockVersion'),
       onSuccess: result => {
         document.querySelector('#task_status').innerText = result.task_status;
         document.querySelector('#task_status_short').innerText = result.task_status_short;

app/assets/javascripts/task_list.js

@@ -30,11 +30,7 @@ export default class TaskList {
     // Prevent duplicate event bindings
     this.disable();
     $(this.taskListContainerSelector).taskList('enable');
-    $(document).on(
-      'tasklist:changed',
-      this.taskListContainerSelector,
-      this.update.bind(this),
-    );
+    $(document).on('tasklist:changed', this.taskListContainerSelector, this.update.bind(this));
   }
 
   getTaskListTarget(e = {}) {

app/serializers/merge_request_basic_entity.rb

@@ -11,4 +11,5 @@ class MergeRequestBasicEntity < Grape::Entity
   expose :labels, using: LabelEntity
   expose :assignee, using: API::Entities::UserBasic
   expose :task_status, :task_status_short
+  expose :lock_version, :lock_version
 end

app/views/projects/merge_requests/show.html.haml

@@ -7,7 +7,7 @@
 - page_card_attributes @merge_request.card_attributes
 - suggest_changes_help_path = help_page_path('user/discussions/index.md', anchor: 'suggest-changes')
 
-.merge-request{ data: { mr_action: j(params[:tab].presence || 'show'), url: merge_request_path(@merge_request, format: :json), project_path: project_path(@merge_request.project) } }
+.merge-request{ data: { mr_action: j(params[:tab].presence || 'show'), url: merge_request_path(@merge_request, format: :json), project_path: project_path(@merge_request.project), lock_version: @merge_request.lock_version } }
   = render "projects/merge_requests/mr_title"
 
   .merge-request-details.issuable-details{ data: { id: @merge_request.project.id } }