Imported contributions get matched to soft-deleted contacts when External ID is used to match to contact

Overview

When importing contributions using External ID as the match-to-contact method, contributions can get matched to soft-deleted contacts, which means no error message appears but the contributions do not appear on the expected record.

See https://civicrm.stackexchange.com/questions/38155/possible-bug-when-using-external-id-as-matching-method-imported-contributions for more.

Reproduction steps

1. Soft-delete a contact (put in the trash but no not delete permanently)
2. Create a .csv for contributions import using that soft-deleted record's information, including External ID
3. Import the contributions file
4. Confirm that the contribution has been added to the soft-deleted contact

Current behaviour

Successful import of a contribution to a contact record that is in the trash

Expected behaviour

Behavior should match what happens when you import a contribution using email or Contact ID to match to contact and the contact is soft-deleted: Error line in the import, with an informative error message (E.g., Email address as matching method gives "No matching Contact found for ([EMAIL ADDRESS])"; Contact ID as matching method gives "Invalid Contact ID: contact_id 204 is a soft-deleted contact." Either one of these would be fine!)

Environment information

• Browser: Chrome OS Version 86.0.4240.198 (Official Build) (64-bit)
• CiviCRM: 5.31.0
• PHP: not sure
• CMS: WordPress 5.5.3
• Database: not sure
• Web Server: not sure

Comments

I am working on getting more environment info but I replicated the issue in two demos (dmaster and wpmaster) so I am not sure that's needed.