Fix spec broken by bde19c06

spec/models/users_project_spec.rb

@@ -10,7 +10,7 @@ describe UsersProject do
     let!(:users_project) { create(:users_project) }
     it { should validate_presence_of(:user_id) }
-    it { should validate_uniqueness_of(:user_id).scoped_to(:project_id) }
+    it { should validate_uniqueness_of(:user_id).scoped_to(:project_id).with_message(/already exists/) }
     it { should validate_presence_of(:project_id) }
   end