Index: includes/install.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/install.inc,v
retrieving revision 1.136
diff -u -p -r1.136 install.inc
--- includes/install.inc	21 Jun 2010 02:27:47 -0000	1.136
+++ includes/install.inc	17 Jul 2010 21:26:06 -0000
@@ -237,7 +237,9 @@ function drupal_detect_database_types() 
   require_once DRUPAL_ROOT . '/includes/database/database.inc';
   spl_autoload_register('db_autoload');
   foreach (file_scan_directory(DRUPAL_ROOT . '/includes/database', '/^[a-z]*$/i', array('recurse' => FALSE)) as $file) {
-    $drivers[$file->filename] = $file->uri;
+    if (file_exists($file->uri . '/database.inc')) {
+      $drivers[$file->filename] = $file->uri;
+    }
   }
 
   foreach ($drivers as $driver => $file) {
Index: modules/system/system.install
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.install,v
retrieving revision 1.490
diff -u -p -r1.490 system.install
--- modules/system/system.install	14 Jul 2010 20:30:09 -0000	1.490
+++ modules/system/system.install	17 Jul 2010 21:26:06 -0000
@@ -141,27 +141,29 @@ function system_requirements($phase) {
     $requirements['php_extensions']['value'] = $t('Enabled');
   }
 
-  // Test for PDO (database).
-  $requirements['database_extensions'] = array(
-    'title' => $t('Database support'),
-  );
-
-  // Test for at least one suitable PDO extension, if PDO is available.
-  $database_ok = extension_loaded('pdo');
-  if ($database_ok) {
-    $drivers = drupal_detect_database_types();
-    $database_ok = !empty($drivers);
-  }
-
-  if (!$database_ok) {
-    $requirements['database_extensions']['value'] = $t('Disabled');
-    $requirements['database_extensions']['severity'] = REQUIREMENT_ERROR;
-    $requirements['database_extensions']['description'] = $t('Your web server does not appear to support any common PDO database extensions. Check with your hosting provider to see if they support PDO (PHP Data Objects) and offer any databases that <a href="@drupal-databases">Drupal supports</a>.', array(
-      '@drupal-databases' => 'http://drupal.org/node/270#database',
-    ));
-  }
-  else {
-    $requirements['database_extensions']['value'] = $t('Enabled');
+  if ($phase != 'runtime') {
+    // Test for PDO (database).
+    $requirements['database_extensions'] = array(
+      'title' => $t('Database support'),
+    );
+
+    // Test for at least one suitable PDO extension, if PDO is available.
+    $database_ok = extension_loaded('pdo');
+    if ($database_ok) {
+      $drivers = drupal_detect_database_types();
+      $database_ok = !empty($drivers);
+    }
+
+    if (!$database_ok) {
+      $requirements['database_extensions']['value'] = $t('Disabled');
+      $requirements['database_extensions']['severity'] = REQUIREMENT_ERROR;
+      $requirements['database_extensions']['description'] = $t('Your web server does not appear to support any common PDO database extensions. Check with your hosting provider to see if they support PDO (PHP Data Objects) and offer any databases that <a href="@drupal-databases">Drupal supports</a>.', array(
+        '@drupal-databases' => 'http://drupal.org/node/270#database',
+      ));
+    }
+    else {
+      $requirements['database_extensions']['value'] = $t('Enabled');
+    }
   }
 
   // Test PHP memory_limit