Always return arrays from get_post_ancestors(). Return an array when passed a value that evaluates to false.

props dannydehaan.
fixes #22882 for trunk.
Test: [1177/tests].



git-svn-id: http://core.svn.wordpress.org/trunk@23212 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/post.php

@@ -682,7 +682,7 @@ final class WP_Post {
  */
 function get_post_ancestors( $post ) {
 	if ( ! $post )
-		return false;
+		return array();
 
 	$post = get_post( $post );