Ticket #13328: use_https_preview.diff

wp-admin/includes/meta-boxes.php

@@ -40 +40 @@
         $preview_link = esc_url(get_permalink($post->ID));
         $preview_button = __('Preview Changes');
 } else {
-        $preview_link = esc_url(apply_filters('preview_post_link', add_query_arg('preview', 'true', get_permalink($post->ID))));
+        $preview_link = esc_url(apply_filters('preview_post_link', add_query_arg('preview', 'true', home_url( ( 'page' == $post->post_type ? '?page_id=' : '?p=' ) . $post->ID, ( is_ssl() ? 'https' : 'http' ) ))));
         $preview_button = __('Preview');
 }
 ?>