#320127 by matt2000: Fix bug with file_check_directory() being passed a function by-reference.

modules/simpletest/drupal_web_test_case.php

@@ -719,7 +719,8 @@ function setUp() {
     // Use temporary files directory with the same prefix as database.
     $this->original_file_directory = file_directory_path();
     variable_set('file_directory_path', file_directory_path() . '/' . $db_prefix);
-    file_check_directory(file_directory_path(), TRUE); // Create the files directory.
+    $directory = file_directory_path();
+    file_check_directory($directory, TRUE); // Create the files directory.
   }
 
   /**