modified_date not update on delete or restore contact

modified_date of contact (civicrm_contact table) is not updated when contact is deleted or restored.

DB schema (Contact/DAO/Contact.php) suggests modified_date (timestamp) should be updated on every change (line 1302: 'default' => 'CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP',)

But function contactTrashRestore (CRM/Contact/BAO/Contact.php line 1076) is calling
$contact->copyValues($updateParams); (line 1090)
which copies all fields values, including (old) modified_date, to be saved on update, preventing "ON UPDATE CURRENT_TIMESTAMP" to apply.

I can see three solutions:
1. add
unset($contact->modified_date); // to let ON UPDATE CURRENT_TIMESTAMP happen in DB
in function contactTrashRestore (CRM/Core/BAO.php line 1091)

2. add
if(isset($fields['modified_date'])) unset ($fields['modified_date']);
in function copyValues (CRM/Core/DAO.php line 580)

3. add a DB trigger with
// Update timestamp for civicrm_contact itself
if ($tableName == NULL || $tableName == self::getTableName())

{ $info[] = array( 'table' => array(self::getTableName()), 'when' => 'AFTER', 'event' => array('UPDATE'), 'sql' => "\nSET NEW.modified_date = CURRENT_TIMESTAMP;\n", ); }

First solution seems lighter. Please confirm it is the correct approach and I can make a patch
(#1 will only impact contact Trash and Restore and not other possible changes in contact when using copyValues function in Contact/BAO).

Thanks