Deleting users fires an email despite a booking rule being in place

[danbuntu]

Describe the bug
I'm not sure if this is a bug or a misunderstanding on my part but...

I have a booking rules setup to send an email when I user is deleted from the booking. This works as expected.

However a second email is also sent. This message uses the lang string deletedtextmessage which also doesn't seem to go through format_string, as in the email is rendered with {a->title} etc in it.

Commenting out line 783 of classes/booking_option.php stops this second email from sending.

I suspect this is part of the legacy emails system.

Versions uses
Moodle version: 4.1
Booking version: 8.8.3

To Reproduce
Steps to reproduce the behavior:

1. Set up a booking rule with the event 'booking option cancelled for/by user'
2. Booked the user in
3. Delete the user booking using the 'Delete repsonses' button on report.php
4. Get the booking rule email and rejoice
5. Get the second deleted message and weep

Expected behavior
One email sent
Either by the booking rule
Or the deleted email automatically turned off when legacy emails are turned off.
Or the ability to toggle off the sending of the deleted email
Or automatically turned of when legacy emails are disabled

[dasistwas]

@danbuntu Could you check if this is still the case with version 8.9.16 : https://github.com/Wunderbyte-GmbH/moodle-mod_booking/tags