old_contents: #
  # Copyright (c) 2011 rPath, Inc.
  #
  # All Rights Reserved
  #
  
  BAD_REQUEST = 400
  NOT_FOUND = 404
  INTERNAL_SERVER_ERROR = 500
  
  class RbuilderError(Exception):
      "An unknown error has occured."
  
      status = INTERNAL_SERVER_ERROR 
  
      def __init__(self, **kwargs):
          cls = self.__class__
          self.msg = cls.__doc__
          self.kwargs = kwargs
  
      def __str__(self):
          try:
              return self.msg % self.kwargs
          except TypeError:
              return self.msg
  
  class CollectionPageNotFound(RbuilderError):
      "The requested page of the collection was not found."
      status = NOT_FOUND
  
  class UknownFilterOperator(RbuilderError):
      "%(filter)s is an invalid filter operator."
      status = BAD_REQUEST
  
  class InvalidFilterValue(RbuilderError):
      "%(value)s in an invalid value for filter operator %(filter)s"
      status = BAD_REQUEST
  
new_contents: #
  # Copyright (c) 2011 rPath, Inc.
  #
  # All Rights Reserved
  #
  
  BAD_REQUEST = 400
  NOT_FOUND = 404
  INTERNAL_SERVER_ERROR = 500
  
  class RbuilderError(Exception):
      "An unknown error has occured."
  
      status = INTERNAL_SERVER_ERROR 
  
      def __init__(self, **kwargs):
          cls = self.__class__
          self.msg = cls.__doc__
          self.kwargs = kwargs
  
      def __str__(self):
          try:
              return self.msg % self.kwargs
          except TypeError:
              return self.msg
  
  class CollectionPageNotFound(RbuilderError):
      "The requested page of the collection was not found."
      status = NOT_FOUND
  
  class UnknownFilterOperator(RbuilderError):
      "%(filter)s is an invalid filter operator."
      status = BAD_REQUEST
  
  class InvalidFilterValue(RbuilderError):
      "%(value)s in an invalid value for filter operator %(filter)s"
      status = BAD_REQUEST
  
subject: Fix typo in exception name