Send sane HTTP response in showpic on error
Currently, if showpic.php requests fail, exceptions are thrown. Those are
usually converted to a HTTP response 500 (internal server error) by the
production exception handler. Crawlers react on 500 by trying to index
the resource again later.
This is changed to now set specific response codes. If the paramters are
incorrect or broken, an 410 (Gone) will be sent, informing users and
crawlers that the resource is not available under this URL. Crawlers
like googleBot will then stop requesting the resource.
In case all parameters are ok, but the image itself is not found, a 404
will be sent to the client. Crawlers will try to index the resource
again only if there are still links pointing to the resource.
Updated by Christian Kuhn about 10 years ago
Will result in a 410 after the patch, and was an exception before.