diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index 7b3e2e03d54a01f95c483c6b9d22afe1582fc3d2..663d53b635d86284c6ccce9af1c85e95a7414138 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -716,7 +716,7 @@ function drupal_settings_initialize() {
   global $base_url, $base_path, $base_root, $script_path;
 
   // Export these settings.php variables to the global namespace.
-  global $databases, $cookie_domain, $conf, $installed_profile, $db_url, $db_prefix, $drupal_hash_salt, $is_https, $base_secure_url, $base_insecure_url, $config_directories;
+  global $databases, $cookie_domain, $conf, $installed_profile, $db_prefix, $drupal_hash_salt, $is_https, $base_secure_url, $base_insecure_url, $config_directories;
   $conf = array();
 
   // Make conf_path() available as local variable in settings.php.
diff --git a/core/includes/install.core.inc b/core/includes/install.core.inc
index 9d683982738dbc725b32f83221edcd05a5791f2e..ec5ec0eb05ff1e2a863cf8c9ea59cd8be34b99cd 100644
--- a/core/includes/install.core.inc
+++ b/core/includes/install.core.inc
@@ -392,11 +392,8 @@ function install_begin_request(&$install_state) {
   else {
     $task = NULL;
 
-    // Do not install over a configured settings.php. Check the 'db_url'
-    // variable in addition to 'databases', since previous versions of Drupal
-    // used that (and we do not want to allow installations on an existing site
-    // whose settings file has not yet been updated).
-    if (!empty($GLOBALS['databases']) || !empty($GLOBALS['db_url'])) {
+    // Do not install over a configured settings.php.
+    if (!empty($GLOBALS['databases'])) {
       throw new Exception(install_already_done_error());
     }
   }