bug in latte {ifchanged }?

may be i am blind, but i think it is bug

clean project with create-project nette/web-project test

renderDefault –

function renderDefault()	{

		$data = [];

		function addData($id)	{

			$item = new Nette\Utils\ArrayHash;
		        $item->id = $id * 10;
	        	$item->flag = intdiv($id,3);
		        $item->name = "Name $id";
			return $item;
		}


		for ($x = 1; $x<15; $x++)
			$data[$x] = addData($x);

		dump($data);

		$this->template->data = $data;
	}

default.latte

{* This is the w/lcome page, you can delete it *}

{block content}

<style>

table {

	border: 1px solid #006699;
	border-collapse:collapse;
}

table td, table th {

	border: 1px solid #006699;
	padding: 5px 5px 5px 5px;
	text-align: center;


</style>


<table>
<tr>
	<th> first
	<th> id
	<th> flag
	<th> name
	<th> flg changed

{foreach $data as $item}

<tr>
	{if !$iterator->first}
		{ifchanged $item->flag}
				<td colspan="5"> separator {ifchanged $item->flag} Y {/ifchanged}
			<tr>
		{/ifchanged}
	{/if}

	<td> {if !$iterator->first} A {else} N {/if}
	<td> {$item->id}
	<td> {$item->flag}
	<td> {$item->name}
	<td> changed: {ifchanged $item->flag} Y {/ifchanged}

	<br>

{/foreach}

output

I thing the first does not have to be there