bug#25451: 24.5; Freeze after while-keyword in sh-mode

[Noam Postavsky]

On Sat, Jan 14, 2017 at 3:54 PM, Elias Schwerdtfeger
<nachtwaechter@tamagothi.de> wrote:
>
> While typing the following, rather ordinary shell script in sh-mode,
> Emacs freezes and consumes full CPU. I had to kill the process.
>
> --- snip ---
> #!/bin/sh
> ########################################################################
> #
> # location-cascade
> # $Id$
> #
> # Requires 'lynx'
> #
> ########################################################################
>
> # User-agent
> # internet exploiter 10 for best results from spammy sites ;)
> UA='Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.1; WOW64; Trident/6.0)'
>
> httpcode=0
> uri=$1
> while
> --- snip ---
>
> The bug is fully reproducible after recover-this-buffer.

I'm sure what this means, and I'm not able to reproduce this.

Is this reproducible from emacs -Q?
Can you reproduce it by just copying that text into a sh-mode buffer,
or does it only happen while typing?
Can you get a backtrace if you send SIGUSR2 to Emacs when it's stuck?