commit d155d7cb39079f8a83a68f601f1f7bc3b55958a5
Author: Joel Pittet <joel@pittet.ca>
Date:   Thu Sep 12 16:35:38 2013 -0700

    remove duplicate string

diff --git a/core/lib/Drupal/Core/Template/AttributeBoolean.php b/core/lib/Drupal/Core/Template/AttributeBoolean.php
index 839eaf0..23efced 100644
--- a/core/lib/Drupal/Core/Template/AttributeBoolean.php
+++ b/core/lib/Drupal/Core/Template/AttributeBoolean.php
@@ -8,8 +8,6 @@
 namespace Drupal\Core\Template;
 use Drupal\Component\Utility\String;
 
-use Drupal\Component\Utility\String;
-
 /**
  * A class that defines a type of boolean HTML attribute.
  *