Chaining desination across multiple pages

In Drupal 4.6, when user_login() outputs the login form, it uses the code:

   return form($output, 'post', url('user/login', drupal_get_destination()));

This sends the user to back to the current page after logging in. This works well for the standard User Login block which appears on normal pages and displays a user/pass/submit form.

I have a custon User Login block which just has a "Log in" text link which points to "user" to generate a page containing only the login form. I can add a destination query to my link but the code above doesn't use it; it always sends the user back to the "user" page after logging in, instead of back to the page on which they clicked "Log in".

I fixed this by having user_login() propagate the destination query if it is present:

  if ($_REQUEST['destination']) {
    $dest = 'destination='.urlencode($_REQUEST['destination']);
  } else {
    $dest = drupal_get_destination();
  }
  return form($output, 'post', url('user/login', $dest));

This works fine. Is there any reason drupal_get_destination() should not ALWAYS do this? Is 4.7 any different?

Thanks,

Barry