Fix bug linked product position not updated if product link already exists

Author: jalogut

app/code/Magento/CatalogImportExport/Model/Import/Product.php

@@ -1230,15 +1230,15 @@ protected function _saveLinks()
                                         'linked_product_id' => $linkedId,
                                         'link_type_id' => $linkId,
                                     ];
-                                    if (!empty($linkPositions[$linkedKey])) {
-                                        $positionRows[] = [
-                                            'link_id' => $productLinkKeys[$linkKey],
-                                            'product_link_attribute_id' => $positionAttrId[$linkId],
-                                            'value' => $linkPositions[$linkedKey],
-                                        ];
-                                    }
-                                    $nextLinkId++;
                                 }
+                                if (!empty($linkPositions[$linkedKey])) {
+                                    $positionRows[] = [
+                                        'link_id' => $productLinkKeys[$linkKey],
+                                        'product_link_attribute_id' => $positionAttrId[$linkId],
+                                        'value' => $linkPositions[$linkedKey],
+                                    ];
+                                }
+                                $nextLinkId++;
                             }
                         }
                     }