commit 20a78e3bc9c49cdfc03aa6056b17736855a74335
Author: fago <nuppla@zites.net>
Date:   Sun Jun 1 14:08:01 2014 -0500

    Improved entity query to check for the sql interface first.

diff --git a/core/lib/Drupal/Core/Entity/Query/Sql/Tables.php b/core/lib/Drupal/Core/Entity/Query/Sql/Tables.php
index 54664d1..6926603 100644
--- a/core/lib/Drupal/Core/Entity/Query/Sql/Tables.php
+++ b/core/lib/Drupal/Core/Entity/Query/Sql/Tables.php
@@ -259,13 +259,13 @@ protected function addJoin($type, $table, $join_condition, $langcode) {
    */
   protected function getTableMapping($table, $entity_type_id) {
     $storage = $this->entityManager->getStorage($entity_type_id);
-    // @todo Stop calling drupal_get_schema() once menu links are converted
-    //   to the Entity Field API. See https://drupal.org/node/1842858.
-    $schema = drupal_get_schema($table);
-    if (!$schema && $storage instanceof SqlEntityStorageInterface) {
+    if ($storage instanceof SqlEntityStorageInterface) {
       $mapping = $storage->getTableMapping()->getAllColumns($table);
     }
     else {
+      // @todo Stop calling drupal_get_schema() once menu links are converted
+      //   to the Entity Field API. See https://drupal.org/node/1842858.
+      $schema = drupal_get_schema($table);
       $mapping = array_keys($schema['fields']);
     }
     return array_flip($mapping);