Fix a flaky feature spec

Signed-off-by: Rémy Coutable <remy@rymai.me>

spec/features/projects/branches/user_deletes_branch_spec.rb

@@ -4,7 +4,7 @@ require "spec_helper"
 
 describe "User deletes branch", :js do
   set(:user) { create(:user) }
-  set(:project) { create(:project, :repository) }
+  let(:project) { create(:project, :repository) }
 
   before do
     project.add_developer(user)
@@ -20,6 +20,8 @@ describe "User deletes branch", :js do
       accept_alert { find(".btn-remove").click }
     end
 
+    wait_for_requests
+
     expect(page).to have_css(".js-branch-improve\\/awesome", visible: :hidden)
   end
 end