DNS settings affect image display

I recently had a situation where I used taxonomy_image on a site which was made live, and the images did not display, all failing with getimagesize() problems. The cause was that although my local DNS had updated, the server's DNS had not, and the module uses full URLs to get the images (6.x-1.6 taxonomy_image.module line 267, I think). The server was querying the full URL and being directed to a totally different IP address.

I believe that a better behaviour here would be to use a relative path instead of a full URL. Is this possible?