CiviCRM 5.49.1, Emails are sent to EVERYONE if any Scheduled Reminder had a "Limit or Add Recipients" (limit_to) value of NULL, which is changed to "0" ("Also Include") during the database upgrade

CiviCRM 5.49.1, Emails are sent to EVERYONE if any Scheduled Reminder had a Limit or Add Recipients (limit_to) value of NULL, which is changed to 0 (Also Include) during the database upgrade. This enables the Also Include option which will then email ALL group(s) selected for the Group field.

The limit_to value should remain NULL post-upgrade. The use of NULL, 1 and 0 for the limit_to select field is not ideal and probably the root cause of this issue, using 1,2,3 would be better IMHO.

Steps to reproduce

1. Check the civicrm_action_schedule table, locate any records which have NULL for the limit_to field, SELECT id FROM civicrm_action_schedule where limit_to IS null
2. Note the record ID for each civicrm_action_schedule
3. Execute the CiviCRM database upgrade for CiviCRM 5.49.1
4. Post upgrade, re-execute the query to check the limit_to field values, SELECT id FROM civicrm_action_schedule where limit_to IS null
5. Zero records are now returned.
6. Check the values of the limit_to in the civicrm_action_schedule for the records from step 1.
7. The limit_to value has now been changed to 0 which equates to the Also Include option

The impact is that the affected Scheduled Reminders may unexpectedly send emails to groups of contacts.

Agileware Ref: CIVICRM-1986

Before CiviCRM database update

Some records have NULL values.

After CiviCRM database update

Same records have been changed from NULL to 0 values.