Editing unique data post input.

I am using the set rules for the form validation.
All is okay but when editing a page it says the slug is taken {of course it is, it belongs to the post I'm editing} but I need it there still obviously because I'm trying to prevent it being shared with another. Anybody have any suggestions as a work around?

PHP Code:

public function set_rules()
    {
        $config = array(
            array(
                'field' => 'title', 
                'label' => 'Title', 
                'rules' => 'trim|min_length[5]|required|xss_clean'
            ),
            array(
                'field' => 'slug', 
                'label' => 'Slug', 
                'rules' => 'trim|min_length[5]|is_unique[pages.slug]|alpha_dash|required|xss_clean'
            ),
            array(
                'field' => 'order', 
                'label' => 'Order', 
                'rules' => 'trim|numeric|required|xss_clean'
            ),
            array(
                'field' => 'body', 
                'label' => 'Body', 
                'rules' => 'trim|min_length[5]|required|xss_clean'
            )
        );
        $this->form_validation->set_rules($config);
    }