Check for existence of l() during install.

platform/drupal/install.inc

@@ -13,10 +13,11 @@ define('PROVISION_DEFAULT_ADMIN_USER', 'admin');
 function install_validate_client_email($client_email) {
   if (!$client_email || !filter_var($client_email, FILTER_VALIDATE_EMAIL)) {
     $invalid_email = 'this.email@is.invalid';
+    $user = function_exists('l') ? l(t('user account'), 'user') : 'user account';
     drush_log(t('Error validating client email `!email`. Please check your !user email. To allow the site installation to proceed, the email `!invalid` has been used instead. Please use the `login` link to change the site admin email to a proper valid address.',
       array(
         '!email' => $client_email,
-        '!user' => l(t('user account'), 'user'),
+        '!user' => $user,
         '!invalid' => $invalid_email,
       )),
       'warning'