Index: wp-includes/shortcodes.php
===================================================================
--- wp-includes/shortcodes.php	(revision 26547)
+++ wp-includes/shortcodes.php	(working copy)
@@ -157,8 +157,11 @@
 			return false;
 
 		foreach ( $matches as $shortcode ) {
-			if ( $tag === $shortcode[2] )
+			if ( $tag === $shortcode[2] ) {
 				return true;
+			} elseif ( isset( $shortcode[5] ) && has_shortcode( $shortcode[5], $tag ) ) {
+				return true;
+			}
 		}
 	}
 	return false;