Index: src/wp-includes/shortcodes.php
===================================================================
--- src/wp-includes/shortcodes.php	(revision 29206)
+++ src/wp-includes/shortcodes.php	(working copy)
@@ -167,8 +167,8 @@
 		foreach ( $matches as $shortcode ) {
 			if ( $tag === $shortcode[2] ) {
 				return true;
-			} elseif ( isset( $shortcode[5] ) && has_shortcode( $shortcode[5], $tag ) ) {
-				return has_shortcode( $shortcode[5], $tag );
+			} elseif ( ! empty( $shortcode[5] ) && has_shortcode( $shortcode[5], $tag ) ) {
+				return true;
 			}
 		}
 	}