The vote button in jira 4.2 seems to have a error:
When trying to unvote my vote, the browser sends a delete request, and this request has an header named Content-Length with an value of 10. This value should be 0 (as there is no body in the request).
Tomcat couldn't care less about this error. But we use WebSEAL as an reverse proxy, and the WebSEAL DOES care - it gives us a 400 (bad request) back.