Had to change setup_redsys because admins can not read the current
encrypt key, thus it is not possible to `set encrypt_key =
coalesce(…, encrypt_key)`.
Not that it did much sense, anyway, as i was already inside the branch
of the if when encrpty_key is null.
However, it seems that this also affects in the `on conflict` update. I
assume this is because `excluded` is some kind of row of the relation
and has the same restrictions.
