Ticket #39238: 39238.diff

src/wp-includes/js/wp-custom-header.js

@@ -54 +54 @@
                                         var handler = this.handlers[ id ];
 
                                         if ( 'test' in handler && handler.test( settings ) ) {
-                                                this.activeHandler = handler.initialize.call( handler, settings );
+                                                this.activeHandler = handler;
+                                                handler.initialize.call( handler, settings );
 
                                                 // Dispatch custom event when the video is loaded.
                                                 trigger( document, 'wp-custom-header-video-loaded' );