ApiError error message if 'code' argument left out, becomes a redundant error

"ApiError: ApiError: Image must be available" is the output if :
    raise exception.ApiError(_('Image must be available'))$

Apparently, the code expects this behavior:

class ApiError(Error):$
    def __init__(self, message='Unknown', code='ApiError'):$
    ...
    super(ApiError, self).__init__('%s: %s' % (code, message))

The output thus becomes redundant and at first glance, I thought I accidentally nested the exception to cause it to repeat itself.

If the 'code' arg is left undefined, the output message should not specify a 'code' portion of the string at all. It should then output something like this instead:

"ApiError: Image must be available"