nodecomment_render default args

The nodecomment_render function has the same comment_render default args. However, the comparison of the $cid argument differs. Whereas comment_render performs:
if ($cid && is_numeric($cid)) {
nodecomment_render performs:
if (is_numeric($cid)) {
As the default $cid argument is 0, this can cause issues. This does not normally show up since node_page_view has $cid set to NULL by default, but under certain circumstances, this bug can show up.