Following recent commits to master branch it is no longer possible to delete issues, an SQL error is triggered

APPLICATION ERROR 401,
Error Description: Database query failed. Error received from database was 1048: Column 'old_value' cannot be null for the query: INSERT INTO mantis_bug_history_table
( user_id, bug_id, date_modified, type, old_value, new_value, field_name )
VALUES
( ?, ?, ?, ?, ?,?, ?).