Parse and return the default value for a date property.

def _parse_date_default_value(property_name, default_value_string):
    """Parse and return the default value for a date property."""
    # OrientDB doesn't use ISO-8601 datetime format, so we have to parse it manually
    # and then turn it into a python datetime object. strptime() will raise an exception
    # if the provided value cannot be parsed correctly.
    parsed_value = time.strptime(default_value_string, ORIENTDB_DATE_FORMAT)
    return datetime.date(parsed_value.tm_year, parsed_value.tm_mon, parsed_value.tm_mday)