UPDATE statement missing for transformation

when using grid-editing normally generate UPDATE statement after editing.

However, if table uses a transformation (for example, a VARCHAR with
a MIME type = text/plain and a Browser transformation = text/plain:
substr), Do not generate UPDATE statement.

As a hint to debug this ================
PMA_getTransformationFunctionAndTransformationOptions() in insert_edit.lib.php does not
(always?) return an array, or an array with is correct to feed tfeed to $response->addJSON().