The Jenkins connector for Mylyn issues a HEAD / request followed by a GET /api/xml request. When an "Accept-Encoding: gzip" header is included in the requests, Jenkins sends unexpected content as part of the response to the HEAD request which breaks the HTTP connection.

This can be reproduced by running the Jenkins 1.481 and curl:

$ curl -v --keepalive -H "Accept-Encoding: gzip,deflate" --head http://localhost:8080/? http://localhost:8080/?

> HEAD /? HTTP/1.1
...
< HTTP/1.1 200 OK
< Set-Cookie: JSESSIONID.e8d41638=6c7970ab0aa9ccf39d999cdbe95f53d4; Path=/; <

• Connection #0 to host localhost left intact
• Connection #0 seems to be dead!
• Closing connection #0
• About to connect() to localhost port 8080 (#0)
• Trying 127.0.0.1... connected
  > HEAD /? HTTP/1.1

Instead of keeping the connection alive curl closes it because the response wasn't valid.

This problem breaks the Jenkins connector for Mylyn: https://bugs.eclipse.org/bugs/show_bug.cgi?id=376468