This fix optionally reverts CAS-1065. See CAS-1166 and CAS-1168.
Cleaned up my comment, added JavaDoc to the new method.
Merge pull request #322 from Unicon/CAS-1166-4.x

CAS-1166/1168 (4.x) login form is not shown on error of Spnego/login form is not shown on error of Spnego