We occasionally observe wrong response code 401 sent by Gerrit (current stable-2.16 version) when authentication of REST request fails since LDAP was shortly not available. If Gerrit cannot authenticate the request since the authentication backend wasn't reachable it should respond with 503 to signal the client it should retry later. Issue: Issue 12786 Change-Id: I159fa98ab7f2b3c8166648ff90da2554aeadd276