[FIX] mail: avoid concurrent update of notifications

When sending notifications by batch one notification email can be send
up to 50 people. For one mail_mail entry to handle 50 emails can be sent
as those are sent independently for each recipient.

In some cases a bounce may occur while the whole batch of recipients is
not completely mailed. In that case the mailgateway will update the
notification status to bounced. When the cron finishes to send the whole
batch of emails it tries to update the notifications of all recipients.
However as a notification has already been updated due to the bounce we
face a concurrent update, meaning the transaction is rollbacked.

Emails have been sent but notifications are not considered as sent as they
have not been updated accordingly. Next time the cron runs it will send the
same batch again, with probably the same bounce and rollback. We could
therefore face an email loop.

This commit add test for this use case.

This commit is linked to task ID 1893054.

0 files changed, 0 insertions, 0 deletions