Ticket #5698: modified.diff

wp-includes/post.php

@@ -1062 +1062 @@
                         $post_date_gmt = '0000-00-00 00:00:00';
         }
 
-        if ( $update ) {
+        if ( $update || '0000-00-00 00:00:00' == $post_date ) {
                 $post_modified     = current_time( 'mysql' );
                 $post_modified_gmt = current_time( 'mysql', 1 );
         } else {