Dispatch needed JS when creating a new MR in diff view

app/assets/javascripts/dispatcher.js.es6

@@ -118,6 +118,7 @@ const ShortcutsBlob = require('./shortcuts_blob');
           new gl.IssuableTemplateSelectors();
           break;
         case 'projects:merge_requests:new':
+        case 'projects:merge_requests:new_diffs':
         case 'projects:merge_requests:edit':
           new gl.Diff();
           shortcut_handler = new ShortcutsNavigation();

app/controllers/projects/application_controller.rb

@@ -83,7 +83,6 @@ class Projects::ApplicationController < ApplicationController
   end
 
   def apply_diff_view_cookie!
-    @show_changes_tab = params[:view].present?
     cookies.permanent[:diff_view] = params.delete(:view) if params[:view].present?
   end
 

app/controllers/projects/merge_requests_controller.rb

@@ -245,6 +245,7 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     respond_to do |format|
       format.html do
         define_new_vars
+        @show_changes_tab = true
         render "new"
       end
       format.json do
@@ -613,6 +614,8 @@ class Projects::MergeRequestsController < Projects::ApplicationController
 
     @labels = LabelsFinder.new(current_user, project_id: @project.id).execute
 
+    @show_changes_tab = params[:show_changes].present?
+
     define_pipelines_vars
   end
 

changelogs/unreleased/27920-both-wip-messages-showing.yml

@@ -0,0 +1,4 @@
+---
+title: Dispatch needed JS when creating a new MR in diff view
+merge_request:
+author: