[WOOCOMMERCE] Get thumbnail without resize

functions.php

<?php
/*
 * @goliver: overwrite function for get thumbnail without resize
 * original in woocommerce-template.php
 */
function woocommerce_get_product_thumbnail( $size = 'shop_catalog', $placeholder_width = 0, $placeholder_height = 0  ) {
	global $post;

	if ( has_post_thumbnail() )
		return get_the_post_thumbnail( $post->ID );
	elseif ( woocommerce_placeholder_img_src() )
	return woocommerce_placeholder_img( $size );
}