Ticket #16550: ticket.16550.diff

post.php

@@ -2903 +2903 @@
         $post_ID = (int) $post_ID;
         $post_type = get_post_type( $post_ID );
         $post_status = get_post_status( $post_ID );
-        // If $post_categories isn't already an array, make it one:
-        if ( !is_array($post_categories) || empty($post_categories) ) {
+        $post_categories = (array) $post_categories;
+        if ( empty($post_categories) ) {
                 if ( 'post' == $post_type && 'auto-draft' != $post_status )
                         $post_categories = array( get_option('default_category') );
                 else