Code review comment for lp:~rackspace-titan/nova/lp795029

Adding to Brian's comment: when you raise the new exception, you need to pass the argument as a keyword; e.g.:
    raise exception.MalformedRequestBody(reason=_("malformed JSON in request body"))

Line 40 also has a capitalization inconsistency: 'Body' should be lowercase 'body'.

Line 66 can be more simply written as:
    message = _("Malformed message body: %(reason)s)"