Remove green outline from `New branch unavailable` button on issue page (!5858)

CHANGELOG

@@ -20,6 +20,7 @@ v 8.11.0
   - Add Issues Board !5548
   - Allow resolving merge conflicts in the UI !5479
   - Improve diff performance by eliminating redundant checks for text blobs
+  - Remove green outline from `New branch unavailable` button on issue page !5858 (winniehell)
   - Ensure that branch names containing escapable characters (e.g. %20) aren't unescaped indiscriminately. !5770 (ewiltshi)
   - Convert switch icon into icon font (ClemMakesApps)
   - API: Endpoints for enabling and disabling deploy keys

app/assets/javascripts/issue.js

@@ -127,7 +127,7 @@
 
     Issue.prototype.initCanCreateBranch = function() {
       var $container;
-      $container = $('div#new-branch');
+      $container = $('#new-branch');
       if ($container.length === 0) {
         return;
       }
@@ -139,7 +139,6 @@
         if (data.can_create_branch) {
           $container.find('.checking').hide();
           $container.find('.available').show();
-          return $container.find('a').attr('disabled', false);
         } else {
           $container.find('.checking').hide();
           return $container.find('.unavailable').show();

app/views/projects/issues/_new_branch.html.haml

 - if can?(current_user, :push_code, @project)
   .pull-right
     #new-branch{'data-path' => can_create_branch_namespace_project_issue_path(@project.namespace, @project, @issue)}
-      = link_to namespace_project_branches_path(@project.namespace, @project, branch_name: @issue.to_branch_name, issue_iid: @issue.iid),
-        method: :post, class: 'btn btn-new btn-inverted has-tooltip', title: @issue.to_branch_name, disabled: 'disabled' do
-        .checking
+      = link_to '#', class: 'checking btn btn-grouped', disabled: 'disabled' do
         = icon('spinner spin')
         Checking branches
-        .available.hide
+      = link_to namespace_project_branches_path(@project.namespace, @project, branch_name: @issue.to_branch_name, issue_iid: @issue.iid),
+        method: :post, class: 'btn btn-new btn-inverted btn-grouped has-tooltip available hide', title: @issue.to_branch_name do
         New branch
-        .unavailable.hide
+      = link_to '#', class: 'unavailable btn btn-grouped hide', disabled: 'disabled' do
         = icon('exclamation-triangle')
         New branch unavailable