Clientless mode with 401 and 403

i have tested a similar APM Policy ("HTTP 401 Response" with all default exits) to get at GIT Client with Basic Auth working. The "HTTP Auth Level" is set to Basic but APM always uses the Negotiate exit of "HTTP 401 Response". instead of sending a 401 to the client you can see a 302 to /vdesk/hangup.php3 in fiddler. We are using the debug mode on that DEV Box but the informations are to poor to find a solution.

(12.1 HF1)