bug#23871: 25.1.50; Undo unexpectedly leads to blank buffer

[Phillip Lord]

On Tue, July 5, 2016 5:36 pm, Eli Zaretskii wrote:

>>> Note the setting of ediprolog-program to simulans.sh. I can reproduce
>>>  the issue with this script. If it does not work for you, please try
>>> a different window size, font, or running Emacs in the terminal.
>>
>> Thanks, I reproduced the problem, and it definitely involves some
>> anomaly in redisplay.  I will look into that aspect of the problem.
>
> This is now fixed on the master branch.  The situation where buffer
> changes happen in a window whose start point is on a continuation line was
> mishandled by code that never expected to find itself in this situation.
> After the fix, the recipe leaves point at the end of line
> 15, in a window that displays that single line at its top.
>
>
> Thanks for the easy to reproduce recipe.

Also, thanks for helping to uncover issues in the undo system, with some
very nice bug reports.