I've found a problem with the fix I posted. When you add a product to the cart that is a variant and has it's own image defined by the variant, the product thumbnail that shows up is incorrect. My cart seems to be displaying seemingly random product thumbnails in the cart for products with specific variant images. I don't have a fix for this short of returning to how the cart was before.
Edit: Fixed
In order to resolve this issue, I had to make it so it called the thumbnail for the productid, and not the variantid. So after you've done my previous fix, you need to do this:
(I do NOT recommend doing this if you want your variant images displayed)
Find in cart.tpl:
Code:
{assign var="imageid" value=$products[product].variantid}{else}{assign var="imageid" value=$products[product].productid}
Replace with:
Code:
{assign var="imageid" value=$products[product].productid}{else}{assign var="imageid" value=$products[product].productid}
This will make it so the thumbnail image that appears in your cart for regular products, and for products with variant images, all display the main product thumbnail image.