bug#71223: 30.0.50; stack overflow after very fast opening and closing of frames

[Eli Zaretskii]

> From: Daniel Clemente <n142857@gmail.com>
> Date: Mon, 27 May 2024 15:21:02 +0000
> Cc: Stefan Monnier <monnier@iro.umontreal.ca>, 71223@debbugs.gnu.org
> 
> I tried the patch, it still happens at the same point, and the stack is ~12k 
> calls, like in previous tests.
> 
> (gdb) xbacktrace
> "sit-for" (0xffc518f8)
> "server--sit-for" (0xffc51a88)
> "server-return-error" (0xffc51c50)
> "server-process-filter" (0xffc51ea8)
> "sit-for" (0xffc53fa8)
> "server--sit-for" (0xffc54138)
> "server-return-error" (0xffc54300)
> "server-process-filter" (0xffc54558)
> "sit-for" (0xffc56658)
> "server--sit-for" (0xffc567e8)
> "server-return-error" (0xffc569b0)

I'm probably missing something, because I don't understand how come
server-process-filter is still being run after we reset the process
filter to nil...