Ticket #21062: 21062.patch

src/wp-includes/template.php

@@ -551 +551 @@
                 $s = esc_attr( $s );
         }
 
+        /**
+         * Filter template file being loaded in load_template
+         *
+         * @since 2.9.0
+         *
+         * @param string $_template_file Path to template file.
+         * @param bool   $require_once   Whether to require_once or require. Default true.
+         */
+        $_template_file = apply_filters( 'template_file', $_template_file, $require_once );
+
         if ( $require_once ) {
                 require_once( $_template_file );
         } else {