Fixed sort by position with flat tables when category filter is not applied (#2637)

Author: elidrissidev

app/code/core/Mage/Catalog/Model/Resource/Product/Collection.php

@@ -1525,9 +1525,6 @@ public function addAttributeToSort($attribute, $dir = self::SORT_ORDER_ASC)
                 $this->getSelect()->order($this->_getAttributeFieldName($attribute) . ' ' . $dir);
                 return $this;
             }
-            if ($this->isEnabledFlat()) {
-                $this->getSelect()->order("cat_index_position {$dir}");
-            }
             // optimize if using cat index
             $filters = $this->_productLimitationFilters;
             if (isset($filters['category_id']) || isset($filters['visibility'])) {