Ticket #23776: 23776.patch

wp-includes/class-wp-embed.php

@@ -308 +308 @@
          */
         public function autoembed_callback( $match ) {
                 $oldval = $this->linkifunknown;
-                $this->linkifunknown = false;
                 $return = $this->shortcode( array(), $match[1] );
-                $this->linkifunknown = $oldval;
 
-                return "\n$return\n";
+                return strpos( $return, '<iframe' ) !== false ? "\n$return\n" : $return;
         }
 
         /**