wp_nav_menu in Wordpress 3.6 ignores parameters or am I doing somethign wrong?

wp_nav_menu in Wordpress 3.6 ignores parameters or am I doing somethign
wrong?

I have this code in my templates:
<?php wp_nav_menu( array( 'container' => '' ) ); ?>
It outputs the menu but wrapped in <div class="menu"> Az I understand the
documentation page it should not output the .