matejl

Found the solution … you need to edit wp-admin/includes/media.php

function image_link_input_fields($post, $url_type = '') {

	//$file = wp_get_attachment_url($post->ID);
	$aFile = wp_get_attachment_image_src($post->ID, 'large');
	$file = $aFile[0];

	$link = get_attachment_link($post->ID);
	...

Problem with this solution is if you modify image (reupload image with different dimensions) the link will become invalid.