Deleting an "empty folder" object causes files under the same prefix to be deleted erroneously

[davidparks21]

Reproduce this issue as follows (replace BUCKETNAME).

> touch tmp.txt
> s4cmd put tmp.txt "s3://BUCKETNAME/bugcheck/"    # create an empty directory marker
> s4cmd put tmp.txt s3://BUCKETNAME/bugcheck/file  # create any file under that path

# ls shows both an empty directory file and a file under that path
> s4cmd ls s3://BUCKETNAME/bugcheck
2021-03-31 19:41 0 s3://BUCKETNAME/bugcheck/
2021-03-31 19:41 0 s3://BUCKETNAME/bugcheck/file

# delete just the empty directory marker (no recursive options set), we DON'T want to delete `file`, but both are deleted
> s4cmd del "s3://BUCKETNAME/bugcheck/"
Delete s3://BUCKETNAME/bugcheck/
Delete s3://BUCKETNAME/bugcheck/file

In the example above only the object s3://BUCKETNAME/bugcheck/ should be deleted, but s3://BUCKETNAME/bugcheck/file gets deleted as well unexpectedly.