bug#47052: 28.0.50; Segfault opening certain python file

[Eli Zaretskii]

> From: J K sanchez <1994jorgesanchez@gmail.com>
> Date: Wed, 10 Mar 2021 15:54:03 +0000
> 
> I found my emacs crashed when opening certain file. It's a python file i 
> can't share but other python files open nicely. 
> When using emacs -Q it opens without problems.
> I found this in gdb when using bt full which was stuck in a loop and was too 
> long.
> a part of (gdb) bt full gives:
> #30522 0x0000557f5a97f600 in substitute_object_recurse (subst=0x7ffd34af9380,
> subtree=0x557f615b52d3) at lisp.h:730

It's an infinite recursion, but I doubt we could do anything about it
without a way to reproduce the problem.  If you can somehow produce a
file that is a derivative of the one you cannot share, and post it,
that would be good.

Thanks.