MT - fix, missed in previous merge

git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@8516 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/security/authentication/AuthenticationServiceImpl.java

@@ -110,6 +110,8 @@ public class AuthenticationServiceImpl extends AbstractAuthenticationService
     {
         try
         {
+            // clear context - to avoid MT concurrency issue (causing domain mismatch) - see also 'validate' below
+            clearCurrentSecurityContext();
             preAuthenticationCheck(userName);
         	authenticationComponent.authenticate(userName, password);
         }