This is the Samba 4 version of bug 6100 Microsoft Open Protocol Document MS-NRPC NetrLogonDummyRoutine1, section 3.5.4.9.5. For win7 this is renamed NetrLogonGetCapabilities – opnum 21, see section 3.5.4.3.10 - Function call to test for a man-in-the-middle attack, this was first implemented in win2k. - If Samba supported the end-point, but not the method, and returned “status not implemented”, then the response is secure and we would downgrade to prior behavior. In short, Samba needs to be returning STATUS_NOT_IMPLEMENTED rather than returning an unauthenticated RPC layer error.
Should be fixed with commit 94abbead1b76e7aafee8c59233b096a3f03b35c8
Ok, then mark it as "FIXED".