write-ins yield too many ranks in ranking poll

A ranking poll that has had one or more write-ins submitted by voters presents future voters with more rankings to assign than choices to choose from if "Display write-in votes as choices for future voters" option is not selected for the poll.

In ranking.inc, I replaced
$num_choices = count($node->choice);
with

    $num_choices = 0;
    foreach($node->choice as $choice) {
    	if(!$choice['writein']) {
    		$num_choices++;
    	}
    }
    // add 1 if write-ins are enabled
    if($node->writeins) {
    	$num_choices++;
    }

but this does then yields too few rankings if "Display write-in votes as choices for future voters" option is selected.