Do not FATAL and quit when handling an NA or ERR negotiate helper response
without a challenge token.

=== modified file 'src/auth/negotiate/UserRequest.cc'
--- src/auth/negotiate/UserRequest.cc	2013-01-28 16:56:05 +0000
+++ src/auth/negotiate/UserRequest.cc	2013-02-13 00:30:07 +0000
@@ -310,53 +310,51 @@
              * challenge-response nature of the protocol.
              * Just free the temporary auth_user after merging as
              * much of it new state into the existing one as possible */
             usernamehash->user()->absorb(local_auth_user);
             /* from here on we are working with the original cached credentials. */
             local_auth_user = usernamehash->user();
             auth_user_request->user(local_auth_user);
         } else {
             /* store user in hash's */
             local_auth_user->addToNameCache();
         }
         /* set these to now because this is either a new login from an
          * existing user or a new user */
         local_auth_user->expiretime = current_time.tv_sec;
         auth_user_request->user()->credentials(Auth::Ok);
         debugs(29, 4, HERE << "Successfully validated user via Negotiate. Username '" << auth_user_request->user()->username() << "'");
     }
     break;
 
     case HelperReply::Error: {
-        Note::Pointer messageNote = reply.notes.find("message");
-        Note::Pointer tokenNote = reply.notes.find("token");
-        if (tokenNote == NULL) {
-            /* protocol error */
-            fatalf("authenticateNegotiateHandleReply: *** Unsupported helper response ***, '%s'\n", reply.other().content());
-            break;
-        }
-
         /* authentication failure (wrong password, etc.) */
+
+        Note::Pointer messageNote = reply.notes.find("message");
         auth_user_request->denyMessage(messageNote->firstValue());
         auth_user_request->user()->credentials(Auth::Failed);
+
         safe_free(lm_request->server_blob);
-        lm_request->server_blob = xstrdup(tokenNote->firstValue());
+        Note::Pointer tokenNote = reply.notes.find("token");
+        if (tokenNote != NULL)
+            lm_request->server_blob = xstrdup(tokenNote->firstValue());
+
         lm_request->releaseAuthServer();
         debugs(29, 4, HERE << "Failed validating user via Negotiate. Error returned '" << reply << "'");
     }
     break;
 
     case HelperReply::Unknown:
         debugs(29, DBG_IMPORTANT, "ERROR: Negotiate Authentication Helper '" << reply.whichServer << "' crashed!.");
         /* continue to the next case */
 
     case HelperReply::BrokenHelper: {
         /* TODO kick off a refresh process. This can occur after a YR or after
          * a KK. If after a YR release the helper and resubmit the request via
          * Authenticate Negotiate start.
          * If after a KK deny the user's request w/ 407 and mark the helper as
          * Needing YR. */
         Note::Pointer errNote = reply.notes.find("message");
         if (reply.result == HelperReply::Unknown)
             auth_user_request->denyMessage("Internal Error");
         else if (errNote != NULL)
             auth_user_request->denyMessage(errNote->firstValue());