Use replace when both old and new values are one value

Author: kou

lib/active_ldap/base.rb

@@ -1372,7 +1372,7 @@ def collect_modified_attributes(ldap_data, data)
         if k == _dn_attribute
           new_dn_value = value[0]
         else
-          if force_replace?(k)
+          if (v.size == 1 and value.size == 1) or force_replace?(k)
             attributes.push([:replace, k, value])
           else
             removed_values = v - value

test/test_base.rb

@@ -447,8 +447,7 @@ def test_save_with_changes
       assert_equal({
                      :modified => true,
                      :entries => [
-                       [:delete, "cn", {"cn" => [cn]}],
-                       [:add, "cn", {"cn" => ["#{cn}!!!"]}],
+                       [:replace, "cn", {"cn" => ["#{cn}!!!"]}],
                      ],
                    },
                    detect_modify(user) {user.save})