taxonomy_image generates invalid HTML when no image size specified -> workaround

When the Resizing Options Constraint is set to "disabled" in admin/settings/taxonomy_image, then the module outputs invalid IMG tags that do not display at all in Internet Explorer, e.g.

<img src="http://blahblah.net/files/picture.png" alt="Term Name" title="Term Description"  width="" height="" />

The workaround I have verified is to change the constraint to 'Exact' and enter in the height/width for the image. This workaround will not work for tax images of variable size, however.