PHPTemplate overrides are ignored

Summary:
PHPTemplate overrides are ignored when theming nodes that include hook_nodeapi additions

Steps to reproduce:

1. Using the ecommerce module, create a few products out of image nodes
2. In template.php, add an override to theme_node_product, without otherwise modifying the code for that theme function:
   
         function phptemplate_node_product($node, $teaser = 0, $page = 0) {
      [...original contents of theme_node_product goes here... (from product.module, line 13)]
      return $node;
      }

Result:

• When viewing a page of teasers (e.g.: ?q=product), the product's price is only appended to node->teaser for the first node.
• WHen the theme function is left alone, internal to the module, the price is appended to all of the teasers.

configuration:

• Drupal v4.7 RC1
• PHPTemplate
• PHP v5.1.2