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. 
host = headers['host']
    for pattern in [common_pattern, dualstack_pattern, legacy_patterns]:
        match = pattern.match(host)
        if match:
            bucket_name = match.groups()[0]
            break
    
    
    return normalize_bucket_name(bucket_name)
def handle_notification_request(bucket, method, data):
    response = Response()
    response.status_code = 200
    response._content = ''
    if method == 'GET':
        
        result = '<NotificationConfiguration xmlns="%s">' % XMLNS_S3
        if bucket in S3_NOTIFICATIONS:
            notifs = S3_NOTIFICATIONS[bucket]
            for notif in notifs:
                for dest in NOTIFICATION_DESTINATION_TYPES:
                    if dest in notif:
                        dest_dict = {
                            '%sConfiguration' % dest: {
                                'Id': uuid.uuid4(),
                                dest: notif[dest],
                                'Event': notif['Event'],
                                'Filter': notif['Filter']
                            }