858647 - Firefox v20 sends wrong Negotiate token for some non-FQDN requests

Status: RESOLVED DUPLICATE of bug 857291

(Firefox :: Untriaged, defect)

Description

[Dmitry]

User Agent: Mozilla/5.0 (Windows NT 5.1; rv:19.0) Gecko/20100101 Firefox/19.0
Build ID: 20130307023931

Steps to reproduce:

There are two web applications available in the internal network at the following addresses:
http://ibis-t/
http://ibis-t.internal.example.org/
and
http://slice-t/
http://slice-t.internal.example.org/

Both applications use Kerberos authentication with SPNEGO. And all the four above URLs work fine in Firefox v19.0.2
But after updating to Firefox v20.0 the first URL does not work anymore - HTTP 401 is returned instead.

With both short URLs Firefox gets HTTP 401 + "WWW-Authenticate: Negotiate" in the first response. And then the browser repeats the request adding "Authorization: Negotiate <token>" header.
But for some reason Firefox v20 sends NTLM token to http://ibis-t/ rather than SPNEGO token.
On the contrast http://slice-t/ gets correct SPNEGO token and works fine.

Downgrading back to Firefox v19.0.2 fixes the problem with http://ibis-t/

Both FQDN addresses work fine both in v19.0.2 and v20.0.