Fix a JS race in a spec

spec/features/projects/settings/user_changes_default_branch_spec.rb

@@ -15,6 +15,9 @@ describe 'Projects > Settings > User changes default branch' do
     let(:project) { create(:project, :repository, namespace: user.namespace) }
 
     it 'allows to change the default branch', :js do
+      # Otherwise, running JS may overwrite our change to project_default_branch
+      wait_for_requests
+
       select2('fix', from: '#project_default_branch')
 
       page.within '#default-branch-settings' do