Any bucket created through cloudformation will have `"LocationConstraint": null`, implying us-east-1, although in AWS CloudFormation the bucket's region will always match the template's region.
if isinstance(value, dict):
        if len(value) == 1 and 'Ref' in value:
            result = resolve_ref(stack_name, value['Ref'],
                resources, attribute='PhysicalResourceId')
            return result
        elif len(value) == 1 and 'Fn::GetAtt' in value:
            return resolve_ref(stack_name, value['Fn::GetAtt'][0],
                resources, attribute=value['Fn::GetAtt'][1])
        else:
            for key, val in iteritems(value):
                value[key] = resolve_refs_recursively(stack_name, val, resources)
        
        if len(value) == 1 and 'Fn::Join' in value:
            return value['Fn::Join'][0].join(value['Fn::Join'][1])
        if len(value) == 1 and 'Fn::Sub' in value:
            result = value['Fn::Sub'][0]
            for key, val in value['Fn::Sub'][1].items():
                val = resolve_refs_recursively(stack_name, val, resources)
                result = result.replace('${%s}' % key, val)
            return result
    if isinstance(value, list):
        for i in range(0, len(value)):
            value[i] = resolve_refs_recursively(stack_name, value[i], resources)
    return value