Index: modules/simpletest/drupal_web_test_case.php
===================================================================
RCS file: /cvs/drupal/drupal/modules/simpletest/drupal_web_test_case.php,v
retrieving revision 1.25
diff -u -r1.25 drupal_web_test_case.php
--- modules/simpletest/drupal_web_test_case.php	5 Jul 2008 07:19:31 -0000	1.25
+++ modules/simpletest/drupal_web_test_case.php	16 Jul 2008 16:10:33 -0000
@@ -631,6 +631,9 @@
     // Generate temporary prefixed database to ensure that tests have a clean starting point.
     $db_prefix = 'simpletest' . mt_rand(1000, 1000000);
     include_once './includes/install.inc';
+
+    // Avoid exceptions from t() during install if the current language is not 'en'.
+    $GLOBALS['language']->language = 'en';
     drupal_install_system();
 
     // Add the specified modules to the list of modules in the default profile.