Internal server error when handling 302 HTTP status for an image

[doherty]

The URL is: http://mustachify.me/?src=http%3A%2F%2F1.gravatar.com%2Favatar%2Fd89011c93da3548ee26ccb76ccd17dbd%3Fs%3D80%26d%3Dhttp%253A%252F%252Fhashbang.ca%252Fwp-includes%252Fimages%252Fblank.gif%26r%3DR

So, the src attribute, when urldecoded is: http://1.gravatar.com/avatar/d89011c93da3548ee26ccb76ccd17dbd?s=80&d=http%3A%2F%2Fhashbang.ca%2Fwp-includes%2Fimages%2Fblank.gif&r=R

If there is no gravatar for that hash, then it will give a 302 Found and a Location header for gravatar's mirrored copy of whatever url is in the d attribute. When urldecoded, in this case it is http://hashbang.ca/wp-includes/images/blank.gif - and the mirrored copy is at http://i0.wp.com/hashbang.ca/wp-includes/images/blank.gif:

$ wget 'http://1.gravatar.com/avatar/d89011c93da3548ee26ccb76ccd17dbd?s=80&d=http%3A%2F%2Fhashbang.ca%2Fwp-includes%2Fimages%2Fblank.gif&r=R'
--2012-11-10 19:34:42--  http://1.gravatar.com/avatar/d89011c93da3548ee26ccb76ccd17dbd?s=80&d=http%3A%2F%2Fhashbang.ca%2Fwp-includes%2Fimages%2Fblank.gif&r=R
Resolving 1.gravatar.com (1.gravatar.com)... 72.21.91.121, 2606:2800:220:bf1:95:a65:51f:1a94
Connecting to 1.gravatar.com (1.gravatar.com)|72.21.91.121|:80... connected.
HTTP request sent, awaiting response... 302 Found
Location: http://i0.wp.com/hashbang.ca/wp-includes/images/blank.gif [following]
--2012-11-10 19:34:42--  http://i0.wp.com/hashbang.ca/wp-includes/images/blank.gif
Resolving i0.wp.com (i0.wp.com)... 72.21.91.111, 2606:2800:220:1c85:99b:1b56:207e:ea5
Connecting to i0.wp.com (i0.wp.com)|72.21.91.111|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 43 [image/gif]
Saving to: `d89011c93da3548ee26ccb76ccd17dbd?s=80&d=http:%2F%2Fhashbang.ca%2Fwp-includes%2Fimages%2Fblank.gif&r=R'

100%[=======================================================================================================>] 43          --.-K/s   in 0s      

2012-11-10 19:34:42 (2.58 MB/s) - `d89011c93da3548ee26ccb76ccd17dbd?s=80&d=http:%2F%2Fhashbang.ca%2Fwp-includes%2Fimages%2Fblank.gif&r=R' saved [43/43]

It appears that 302s are not handled properly, because this results in an internal server error.