Offsite avatar must end in .jpg etc.

One is forced to strip anything after the .jpg or else one will get
"The URL you specified is invalid." when using "Link off-site:
Enter the URL of the location containing the avatar image you wish to
link to."

This bug is still present in the 3.1 demo.

The files are exactly the same.

$ wget http://www.gravatar.com/avatar/47edd1ee4d973c50bbe7991bb063d09d.jpg?s=80 -O A
$ wget http://www.gravatar.com/avatar/47edd1ee4d973c50bbe7991bb063d09d.jpg -O B
$ sum A B
25586 4 A
25586 4 B

Please ignore that they are from Gravatar. That is beside the point.

"Upload from a URL:
Enter the URL of the location containing the image. The image will be copied to this site." is also affected.