bug#28430: 26.0.50; Segfault on unexpected connection loss

[Eli Zaretskii <eliz@gnu.org>]

> From: Daniel Kraus <daniel@kraus.my>
> Date: Tue, 12 Sep 2017 13:41:20 +0800
> 
> This bug happens with restclient mode but I suspect it happens
> for other packages as well?!
> 
> To reproduce:
> 
> Start in a process to listen on a port, e.g.
> #+BEGIN_SRC sh
> nc -l -p 6543
> #+END_SRC
> 
> Start emacs: `emacs --debug-init -Q`
> 
> Load restclient:
> #+BEGIN_SRC emacs-lisp
> (add-to-list 'load-path "/home/daniel/.emacs.d/elpa/restclient-20170727.825")
> (require 'restclient)
> #+END_SRC
> Open new buffer (e.g. 'test.rest') and `M-x restclient-mode`.
> Type:
> `GET http://127.0.0.1:6543/`
> and then press `C-c C-c`
> 
> Switch to the netcat window and Ctrl-C to break up the connection.
> Emacs segfaults:
> #+BEGIN_QUOTE
> Fatal error 11: Segmentation fault

Can you please run this under GDB, and when Emacs segfaults, produce
the C backtrace and post it here?

Thanks.