[1.2.X] Fixed #15062 -- Documented the fact that managers must be able to be...

        # Default manager is CustomManager, but OtherManager is

        # also available via the "extra_manager" attribute.

Implementation concerns

-----------------------

Whatever features you add to your custom ``Manager``, it must be

possible to make a shallow copy of a ``Manager`` instance; i.e., the

following code must work::

    >>> import copy

    >>> manager = MyManager()

    >>> my_copy = copy.copy(manager)

Django makes shallow copies of manager objects during certain queries;

if your Manager cannot be copied, those queries will fail.

This won't be an issue for most custom managers. If you are just

adding simple methods to your ``Manager``, it is unlikely that you

will inadvertently make instances of your ``Manager`` uncopyable.

However, if you're overriding ``__getattr__`` or some other private

method of your ``Manager`` object that controls object state, you

should ensure that you don't affect the ability of your ``Manager`` to

be copied.

.. _manager-types:

Controlling automatic Manager types