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* Added ALLOW_FOR_RCLONE_BASED_S3_TO_S3_COPY feature to types/file.py to specifically
and ONLY allow rclone based S3-to-S3 copy. For some reason rclone needs s3:ListBucket;
but we limit it to a key prefix set to exactly our upload file destination key.
See more comments in types/file.py/external_creds.