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. 
if method == 'GET':
                return get_cors(bucket)
            if method == 'PUT':
                return set_cors(bucket, data)
            if method == 'DELETE':
                return delete_cors(bucket)
        if query == 'lifecycle' or 'lifecycle' in query_map:
            if method == 'GET':
                return get_lifecycle(bucket)
            if method == 'PUT':
                return set_lifecycle(bucket, data)
        if query == 'replication' or 'replication' in query_map:
            if method == 'GET':
                return get_replication(bucket)
            if method == 'PUT':
                return set_replication(bucket, data)
        if query == 'encryption' or 'encryption' in query_map:
            if method == 'GET':
                return get_encryption(bucket)
            if method == 'PUT':
                return set_encryption(bucket, data)
        if query == 'object-lock' or 'object-lock' in query_map:
            if method == 'GET':
                return get_object_lock(bucket)
            if method == 'PUT':
                return set_object_lock(bucket, data)
        if modified_data is not None or headers_changed:
            return Request(data=modified_data or data, headers=headers, method=method)
        return True
    def get_201_reponse(self, key, bucket_name):