commit 333844627c499becc1b4c7aa23f8c1d830d1d8c2
Author: Damien Tournoud <damien@commerceguys.com>
Date:   Thu Jun 23 13:13:41 2011 +0200

    Issue #212284 by Damien Tournoud: remove unecessary security check in the install configuration form that makes it impossible to reinstall a site that has its name set in settings.php.

diff --git a/includes/install.core.inc b/includes/install.core.inc
index a74dfdf..1c85a3b 100644
--- a/includes/install.core.inc
+++ b/includes/install.core.inc
@@ -1408,13 +1408,6 @@ function install_import_locales(&$install_state) {
  *   The form API definition for the site configuration form.
  */
 function install_configure_form($form, &$form_state, &$install_state) {
-  if (variable_get('site_name', FALSE) || variable_get('site_mail', FALSE)) {
-    // Site already configured: This should never happen, means re-running the
-    // installer, possibly by an attacker after the 'install_task' variable got
-    // accidentally blown somewhere. Stop it now.
-    throw new Exception(install_already_done_error());
-  }
-
   drupal_set_title(st('Configure site'));
 
   // Warn about settings.php permissions risk