For 4.1.8 I just changed it from...
Code:
<a href="product.php?productid={$wl_products[product].productid}&quantity={$wl_products[product].amount}">{if $wl_products[product].is_pimage eq 'W' }{assign var="imageid" value=$wl_products[product].variantid}{else}{assign var="imageid" value=$wl_products[product].productid}{/if}{include file="product_thumbnail.tpl" productid=$imageid image_x=$wl_products[product].pimage_x image_y=$wl_products[product].pimage_y product=$wl_products[product].product tmbn_url=$wl_products[product].pimage_url type=$wl_products[product].is_pimage}</a>
to
Code:
<a href="product.php?productid={$wl_products[product].productid}&quantity={$wl_products[product].amount}">{include file="product_thumbnail.tpl" productid=$wl_products[product].productid image_x=$products[product].tmbn_x|default:$config.Appearance.thumbnail_width image_y=$products[product].tmbn_y product=$products[product].product tmbn_url=$products[product].tmbn_url}</a>
Basically I just took the routine from products_t.tpl and changed "$products[product].productid" to "$wl_products[product].productid". It seems to work fine.