PHPTemplate doesn't load sidebars on Page Not Found errors

When hitting a page not found error the sidebars never get setup in the template. It looks like this is because of the added $show_blocks argument in the phptemplate_page function. When theme() calls phptemplate_page() (for a non-existent page) it passes the $args as array([0] => [1] =>) and I think this must be setting $show_blocks to an empty value.