[skip ci] fix bug where checkmark would not show up on selected user dropdown

app/assets/javascripts/users_select.js

@@ -363,15 +363,20 @@ import eventHub from './sidebar/event_hub';
             },
             updateLabel: $dropdown.data('dropdown-title'),
             renderRow: function(user) {
-              var avatar, img, listClosingTags, listWithName, listWithUserName, selected, username;
+              var avatar, img, listClosingTags, listWithName, listWithUserName, username;
               username = user.username ? "@" + user.username : "";
               avatar = user.avatar_url ? user.avatar_url : false;
 
+              let selected = user.id === parseInt(selectedId, 10);
+
+              if (this.multiSelect) {
                 const fieldName = this.fieldName;
                 const field = $dropdown.closest('.selectbox').find("input[name='" + fieldName + "'][value='" + user.id + "']");
+
                 if (field.length) {
                   selected = true;
                 }
+              }
 
               img = "";
               if (user.beforeDivider != null) {

spec/features/dashboard/issues_spec.rb

@@ -30,6 +30,11 @@ RSpec.describe 'Dashboard Issues', feature: true do
     find('#assignee_id', visible: false).set('')
     find('.js-author-search', match: :first).click
     find('.dropdown-menu-author li a', match: :first, text: current_user.to_reference).click
+    find('.js-author-search', match: :first).click
+
+    page.within '.dropdown-menu-user' do
+      expect(find('.dropdown-menu-author li a.is-active', match: :first, text: current_user.to_reference)).to be_visible
+    end
 
     expect(page).to have_content(authored_issue.title)
     expect(page).to have_content(authored_issue_on_public_project.title)