bug#39962: 27.0.90; Crash in Emacs 27.0.90

[Eli Zaretskii]

> From: Pip Cet <pipcet@gmail.com>
> Date: Sat, 14 Mar 2020 16:15:57 +0000
> Cc: Eli Zaretskii <eliz@gnu.org>, pieter-l@vanoostrum.org, 
> 39962@debbugs.gnu.org
> 
> > The two comments do not seem to agree. Surely second one should say just
> > something like "P must point into block M."
> 
> Thanks! Revised patch attached.

Thanks.  I'd prefer not to duplicate code, though.  Can we teach
live_buffer_holding to disregard whether a buffer is killed or not
based on an additional argument?