Pass $post_id arg directly to get_post_thumbnail_id() from has_post_thumbnail(). The null/get_the_ID() check is already performed at that level of the stack. see #19012.

git-svn-id: http://svn.automattic.com/wordpress/trunk@19029 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/post-thumbnail-template.php

@@ -18,7 +18,6 @@
  * @return bool Whether post has an image attached.
  */
 function has_post_thumbnail( $post_id = null ) {
-	$post_id = ( null === $post_id ) ? get_the_ID() : $post_id;
 	return (bool) get_post_thumbnail_id( $post_id );
 }