Index: install.php
===================================================================
RCS file: /cvs/drupal/drupal/install.php,v
retrieving revision 1.34.2.2
diff -u -F^f -r1.34.2.2 install.php
--- install.php	12 Jul 2007 06:53:03 -0000	1.34.2.2
+++ install.php	17 Oct 2007 19:33:43 -0000
@@ -166,6 +166,10 @@ function install_change_settings($profil
   if ($db_url == 'mysql://username:password@localhost/databasename') {
     $db_user = $db_pass = $db_path = '';
   }
+  elseif (!empty($db_url)) {
+    // Do not install over a configured settings.php.
+    install_already_done_error();
+  }
   $output = drupal_get_form('install_settings_form', $profile, $install_locale, $settings_file, $db_url, $db_type, $db_prefix, $db_user, $db_pass, $db_host, $db_port, $db_path);
   drupal_set_title(st('Database configuration'));
   print theme('install_page', $output);
@@ -506,7 +510,7 @@ function install_already_done_error() {
 
   drupal_maintenance_theme();
   drupal_set_title(st('Drupal already installed'));
-  print theme('install_page', st('<ul><li>To start over, you must empty your existing database.</li><li>To install to a different database, edit the appropriate <em>settings.php</em> file in the <em>sites</em> folder.</li><li>To upgrade an existing installation, proceed to the <a href="@base-url/update.php">update script</a>.</li></ul>', array('@base-url' => $base_url)));
+  print theme('install_page', st('<ul><li>To start over, you must empty your existing database and replace the appropriate <em>settings.php</em> with an unmodified copy.</li><li>To install to a different database, edit the appropriate <em>settings.php</em> file in the <em>sites</em> folder.</li><li>To upgrade an existing installation, proceed to the <a href="@base-url/update.php">update script</a>.</li></ul>', array('@base-url' => $base_url)));
   exit;
 }