Complements rev. 9b1009cd5a to fix the
handling of validation transactions for 3DS-enabled cards.
This handles a few issues:
- make sure to trigger the refund for validation transactions even if
the first feedback we get is the S2S feedback
- feedback URL called by the users' browser should not reset the payment
transaction to 'done' when the refund process has been initiated
- status 81 for "refund pending" should not end up with a transaction in
error. It may be that Ingenico will send a feedback transaction later
or not at all, but the refund is likely to succeed at that point.
Without this commit, validation transactions would never be refunded for
3DS cards.
Remaining issue: the return_url does not seem to be set for those
validation transactions, so the user ends up on the homepage after
completing the 3DS step.