$ python3
Python 3.8.10 (default, Sep 28 2021, 16:10:42) 
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.

>>> object
<class 'object'>

>>> import builtins
>>> builtins.object
<class 'object'>

>>> builtins.object = int
>>> object
<class 'int'>


Python is very much a language about responsibility.  If Django is overriding `__getattribute__` then it is their responsibility to ensure that everything still works properly.  If something doesn't, we file a bug report and/or implement a work-around.

As for side-effect free -- I'm not sure than anything in Python is guaranteed to be side-effect free, except maybe `is`.

There is no bug here, everything is working as intended.