MinIO: InvalidCredsError when trying to retrieve an object

## Summary

When using the `minio` provider and getting an object, the method raises an `libcloud.common.types.InvalidCredsError`, despite the fact that it was able to create a container and upload it the object (so it doesn't look like a credential issue)
100% repro, code to repro the bug is provided

## Detailed Information

libcloud: latest stable, 3.3.1
Python: 3.8.10
OS: Ubuntu 20.04

Here you can find a repo to repro the bug, using `pytest` (Actually there are 2 bugs to report):
https://github.com/Wenzel/libcloud_bug

~~~python3
$ pytest -k test_demo_InvalidCreds
__________________________________________________________________________________________ test_demo_InvalidCreds ___________________________________________________________________________________________

clean_minio_db = , tmp_path = PosixPath('/tmp/pytest-of-wenzel/pytest-22/test_demo_InvalidCreds0')

def test_demo_InvalidCreds(clean_minio_db, tmp_path):
# setup
expected_data = b"data"
with open(tmp_path / "file1.txt", "wb") as f:
f.write(expected_data)
adapter = clean_minio_db
c = adapter.create_container("objects")
# test
ret = adapter.upload_object(tmp_path / "file1.txt", c, "file1")
> obj = adapter.get_object(c, "file1")

tests/test_demo_bug.py:31:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
../../.cache/pypoetry/virtualenvs/libcloud-bug-IT-EyGKG-py3.8/lib/python3.8/site-packages/libcloud/storage/drivers/s3.py:370: in get_object
response = self.connection.request(object_path, method='HEAD')
../../.cache/pypoetry/virtualenvs/libcloud-bug-IT-EyGKG-py3.8/lib/python3.8/site-packages/libcloud/common/base.py:655: in request
response = responseCls(**kwargs)
../../.cache/pypoetry/virtualenvs/libcloud-bug-IT-EyGKG-py3.8/lib/python3.8/site-packages/libcloud/common/base.py:166: in __init__
message=self.parse_error(),
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self =

def parse_error(self):
if self.status in [httplib.UNAUTHORIZED, httplib.FORBIDDEN]:
> raise InvalidCredsError(self.body)
E libcloud.common.types.InvalidCredsError: ''

../../.cache/pypoetry/virtualenvs/libcloud-bug-IT-EyGKG-py3.8/lib/python3.8/site-packages/libcloud/storage/drivers/s3.py:138: InvalidCredsError
------------------------------------------------------------------------------------------- Captured stdout setup -------------------------------------------------------------------------------------------
ca19a7e29a92d875ec58b0285c854403ae5a95433a71e084011d32018a9141d1
----------------------------------------------------------------------------------------- Captured stdout teardown ------------------------------------------------------------------------------------------
libcloud_bug_objectmistmatch_miniodb
========================================================================================== short test summary info ==========================================================================================
FAILED tests/test_demo_bug.py::test_demo_InvalidCreds - libcloud.common.types.InvalidCredsError: ''
~~~

Thanks for your help !

Inizia da tests/test_demo_bug.py e riproduci il fallimento usando pytest -k test_demo_InvalidCreds. Traccia MinIO get_object attraverso s3.py, in particolare S3Response.parse_error e la richiesta HEAD, quindi aggiungi una copertura di regressione che dimostri che il recupero dell’oggetto caricato non solleva InvalidCredsError, mentre gli errori autentici delle credenziali rimangono identificabili.

Scritto dal modello di indicizzazione a partire dal testo della issue.