[8721] introduced some internal field names. We hide them from the list of

    def get_all_field_names(self):

        """

        Returns a list of all field names that are possible for this model

        (including reverse relation names).

        (including reverse relation names). This is used for pretty printing

        debugging output (a list of choices), so any internal-only field names

        are not included.

        """

        try:

            cache = self._name_map

            cache = self.init_name_map()

        names = cache.keys()

        names.sort()

        return names

        # Internal-only names end with "+" (symmetrical m2m related names being

        # the main example). Trim them.

        return [val for val in names if not val.endswith('+')]

    def init_name_map(self):

        """

>>> e1.related.all()

[<Tag: t2>]

# The secret internal related names for self-referential many-to-many fields

# shouldn't appear in the list when an error is made.

>>> SelfRefer.objects.filter(porcupine='fred')

Traceback (most recent call last):

...

FieldError: Cannot resolve keyword 'porcupine' into field. Choices are: id, name, references, related

"""

}