The mod_auth_kerb module for Apache sends a response with "WWW-Authenticate: Nogotiate" but it only accepts raw Kerberos 5 AP-REQ tokens. In order for Java to work with this module, the client side must have "-Dhttp.auth.preference=kerberos" set. This leads to the same problem described in this bug report. Therefore, we probably should not say "This is not of high priority" anymore.
The subCR created for 6u20 is due to 6924535, which is filed by SNCF of France, a P3 bug.