Comment 4 for bug 1630615

no, that alone brought trouble.
current trunk version also has that.
memcached_clone does connect before setting sasl options.

final approach we took and it tested OK:
behavior.cc (memcached_behavior_set):
  case MEMCACHED_BEHAVIOR_BINARY_PROTOCOL:
    if(ptr->flags.binary_protocol != bool(data)) {
      send_quit(ptr); // We need t shutdown all of the connections to make sure we do the correct protocol
    }

memcached.cc (memcached_clone):
  if (LIBMEMCACHED_WITH_SASL_SUPPORT and source->sasl.callbacks)
  {
    if (memcached_failed(memcached_clone_sasl(new_clone, source)))
    {
      memcached_free(new_clone);
      return NULL;
    }
  }

  if (memcached_server_count(source))
  {
    if (memcached_failed(memcached_push(new_clone, source)))
    {
      return NULL;
    }
  }