Hi!

I have noticed that today (25th of Feb) a new version of localstack docker image was pushed to the repository (82c83ff027114060938856eac5dc7be1d534afd0b7711510246de4a76dde2396) and this version fails in my integration tests with an exception:

```
2020-02-25T12:09:44:ERROR:localstack.services.generic_proxy: Error forwarding request: An error occurred (404) when calling the HeadObject operation: Not Found Traceback (most recent call last):
  File "/opt/code/localstack/localstack/services/generic_proxy.py", line 303, in forward updated_response = self.proxy.update_listener.return_response(**kwargs)
  File "/opt/code/localstack/localstack/services/s3/s3_listener.py", line 954, in return_response
send_notifications(method, bucket_name, object_path, version_id)
  File "/opt/code/localstack/localstack/services/s3/s3_listener.py", line 178, in send_notifications
send_notification_for_subscriber(notif, bucket_name, object_path,
  File "/opt/code/localstack/localstack/services/s3/s3_listener.py", line 191, in send_notification_for_subscriber
object_size = s3_client.head_object(Bucket=bucket_name, Key=key).get('ContentLength', 0)
  File "/opt/code/localstack/.venv/lib/python3.8/site-packages/botocore/client.py", line 316, in _api_call
return self._make_api_call(operation_name, kwargs)
  File "/opt/code/localstack/.venv/lib/python3.8/site-packages/botocore/client.py", line 626, in _make_api_call
  raise error_class(parsed_response, operation_name)
botocore.exceptions.ClientError: An error occurred (404) when calling the HeadObject operation: Not Found
```
The same setup in docker-compose works with version 0.10.7 and 0.10.6 without any errors or exceptions. 
bucket_name = 'test-bucket-%s' % short_uid()
        object_key = 'data'
        self.s3_client.create_bucket(Bucket=bucket_name)
        body = 'Hello\r\n\r\n\r\n\r\n'
        headers = """
            Authorization: foobar
            Content-Type: audio/mpeg
            X-Amz-Content-Sha256: STREAMING-AWS4-HMAC-SHA256-PAYLOAD
            X-Amz-Date: 20190918T051509Z
            X-Amz-Decoded-Content-Length: %s
        """ % len(body)
        headers = dict([[field.strip() for field in pair.strip().split(':', 1)]
            for pair in headers.strip().split('\n')])
        data = ('d;chunk-signature=af5e6c0a698b0192e9aa5d9083553d4d241d81f69ec62b184d05c509ad5166af\r\n' +
            '%s\r\n0;chunk-signature=f2a50a8c0ad4d212b579c2489c6d122db88d8a0d0b987ea1f3e9d081074a5937\r\n') % body
        
        url = '%s/%s/%s' % (config.TEST_S3_URL, bucket_name, object_key)
        req = PutRequest(url, to_bytes(data), headers)
        urlopen(req, context=ssl.SSLContext()).read()
        
        downloaded_object = self.s3_client.get_object(Bucket=bucket_name, Key=object_key)
        download_file_object = to_str(downloaded_object['Body'].read())
        self.assertEqual(len(str(download_file_object)), len(body))
        self.assertEqual(str(download_file_object), body)
        
        self._delete_bucket(bucket_name, [object_key])
    def test_s3_put_object_on_presigned_url(self):