Fix updating and disabling merge button when Merge Immediately is clicked

app/views/projects/merge_requests/widget/open/_accept.html.haml

@@ -7,9 +7,9 @@
       .accept-action
         - if @ci_commit && @ci_commit.active?
           %span.btn-group
-            = link_to "#", class: "btn btn-create merge_when_build_succeeds" do
+            = button_tag class: "btn btn-create js-merge-button merge_when_build_succeeds" do
               Merge When Build Succeeds
-            %a.btn.btn-success.dropdown-toggle{ 'data-toggle' => 'dropdown' }
+            = button_tag class: "btn btn-success dropdown-toggle", 'data-toggle' => 'dropdown' do
               %span.caret
               %span.sr-only
                 Select Merge Moment
@@ -23,7 +23,7 @@
                   = icon('warning fw')
                   Merge Immediately
         - else
-          = f.button class: "btn btn-create btn-grouped accept_merge_request #{status_class}" do
+          = f.button class: "btn btn-create btn-grouped js-merge-button accept_merge_request #{status_class}" do
             Accept Merge Request
       - if @merge_request.can_remove_source_branch?(current_user)
         .accept-control.checkbox
@@ -43,7 +43,7 @@
 
   :javascript
     $('.accept_merge_request').on('click', function() {
-      $(this).html("<i class='fa fa-spinner fa-spin'></i> Merge in progress");
+      $('.js-merge-button').html("<i class='fa fa-spinner fa-spin'></i> Merge in progress");
     });
 
     $('.accept-mr-form').on('ajax:send', function() {

spec/features/merge_requests/merge_when_build_succeeds_spec.rb

@@ -21,12 +21,12 @@ feature 'Merge When Build Succeeds', feature: true, js: true do
     end
 
     it 'displays the Merge When Build Succeeds button' do
-      expect(page).to have_link "Merge When Build Succeeds"
+      expect(page).to have_button "Merge When Build Succeeds"
     end
 
     context "Merge When Build succeeds enabled" do
       before do
-        click_link "Merge When Build Succeeds"
+        click_button "Merge When Build Succeeds"
       end
 
       it 'activates Merge When Build Succeeds feature' do
@@ -58,7 +58,7 @@ feature 'Merge When Build Succeeds', feature: true, js: true do
     it 'cancels the automatic merge' do
       click_link "Cancel Automatic Merge"
 
-      expect(page).to have_link  "Merge When Build Succeeds"
+      expect(page).to have_button "Merge When Build Succeeds"
 
       visit_merge_request(merge_request) # Needed to refresh the page
       expect(page).to have_content "Canceled the automatic merge"