Garbage collection of deleted CO fails because of cm_co_announcements fk

The garbage collection job for a deleted CO failed with Finish Summary "SQLSTATE[23000]: Integrity constraint violation: 1451 Cannot delete or update a parent row: a foreign key constraint fails (`biocommons_registry_test`.`cm_co_announcements`, CONSTRAINT `cm_co_announcements_co_announcement_channel_id_fk` FOREIGN KEY (`co_an "

(The rest is cut off).

I removed the foreign key constraint manually using ALTER TABLE, deleted all rows from the cm_co_announcements table (they were all from the CO that was being deleted), and then added back the foreign key constraint with another ALTER TABLE command.

I then rescheduled the garbage collection job and this time it ran to completion and the COs that were queued to be deleted were deleted.

This happened with version 4.3.1.