dynamodbstreams describe-stream shows stream not found but the stream is there in list-streams

Steps to recreate:
1. create dynamodb table, 
```
aws dynamodb create-table --table-name MusicCollection --attribute-definitions AttributeName=Artist,AttributeType=S AttributeName=SongTitle,AttributeType=S --key-schema AttributeName=Artist,KeyType=HASH AttributeName=SongTitle,KeyType=RANGE --provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5 --endpoint http://localhost:4569
```

2. add stream
```
aws dynamodb update-table --table-name MusicCollection --stream-specification StreamEnabled=true,StreamViewType=NEW_IMAGE --endpoint http://localhost:4569
{
    "TableDescription": {
        "TableArn": "arn:aws:dynamodb:eu-central-1:000000000000:table/MusicCollection", 
        "AttributeDefinitions": [
            {
                "AttributeName": "Artist", 
                "AttributeType": "S"
            }, 
            {
                "AttributeName": "SongTitle", 
                "AttributeType": "S"
            }
        ], 
        "ProvisionedThroughput": {
            "NumberOfDecreasesToday": 0, 
            "WriteCapacityUnits": 5, 
            "LastIncreaseDateTime": 0.0, 
            "ReadCapacityUnits": 5, 
            "LastDecreaseDateTime": 0.0
        }, 
        "TableSizeBytes": 0, 
        "TableName": "MusicCollection", 
        "TableStatus": "ACTIVE", 
        "StreamSpecification": {
            "StreamViewType": "NEW_IMAGE", 
            "StreamEnabled": true
        }, 
        "LatestStreamLabel": "2019-09-21T10:47:14.246", 
        "KeySchema": [
            {
                "KeyType": "HASH", 
                "AttributeName": "Artist"
            }, 
            {
                "KeyType": "RANGE", 
                "AttributeName": "SongTitle"
            }
        ], 
        "ItemCount": 0, 
        "CreationDateTime": 1569062831.736, 
        "LatestStreamArn": "arn:aws:dynamodb:eu-central-1:000000000000:table/MusicCollection/stream/2019-09-21T10:47:14.246"
    }
}
```
3. Note LatestStreamARN from output ```"LatestStreamArn": "arn:aws:dynamodb:eu-central-1:000000000000:table/MusicCollection/stream/2019-09-21T10:47:14.246"```

4. List streams:
```
aws dynamodbstreams list-streams --endpoint http://localhost:4570                                                                                                                  
{
    "LastEvaluatedStreamArn": "TODO", 
    "Streams": [
        {
            "TableName": "MusicCollection", 
            "StreamArn": "arn:aws:dynamodb:eu-central-1:000000000000:table/MusicCollection/stream/2019-09-21T10:47:16", 
            "StreamLabel": "TODO"
        }
    ]
}
```
5. Compare StreamARN to step 3.

Expected behavior: they should match (AWS dynamodb/streams behavior)
""" Check whether a valid region is provided, and if not then raise an Exception. """
    auth_header = headers.get('Authorization')
    if not auth_header:
        raise Exception('Unable to find "Authorization" header in request')
    replaced = re.sub(r'.*Credential=([^,]+),.*', r'\1', auth_header)
    if auth_header == replaced:
        raise Exception('Unable to find "Credential" section in "Authorization" header')
    
    
    parts = replaced.split('/')
    region = parts[2]
    if region not in config.VALID_REGIONS:
        raise Exception('Invalid region specified in "Authorization" header: "%s"' % region)
def fix_account_id_in_arns(response, colon_delimiter=':', existing=None, replace=None):
    """ Fix the account ID in the ARNs returned in the given Flask response or string """
    existing = existing or ['123456789', MOTO_ACCOUNT_ID]
    existing = existing if isinstance(existing, list) else [existing]
    replace = replace or TEST_AWS_ACCOUNT_ID
    is_str_obj = is_string_or_bytes(response)
    content = to_str(response if is_str_obj else response._content)
    replace = r'arn{col}aws{col}\1{col}\2{col}{acc}{col}'.format(col=colon_delimiter, acc=replace)
    for acc_id in existing:
        regex = r'arn{col}aws{col}([^:%]+){col}([^:%]*){col}{acc}{col}'.format(col=colon_delimiter, acc=acc_id)
        content = re.sub(regex, replace, content)
    if not is_str_obj:
        response._content = content
        response.headers['content-length'] = len(response._content)
        return response
    return content
def get_s3_client():