non-image files are copied to the image_field thumbs directory

The file should be checked before regenerating the imagefield admin thumbnail because non-image files are copied to the thumbnail directory.

To fix this I added a check to the file mime type to insure it is an image before attempting to regenerate the thumbnail.

6.x--1.0-RC5 and prior have this issue.

fixed in : http://drupal.org/cvs?commit=275410

For users of this module prior to 1.0 you may have to manually remove some files from '/imagefield_thumbs' directory