bug#22295: viper-mode undo bug introduced between Nov 10 and Nov 14

[Jim Meyering]

On Wed, May 18, 2016 at 2:42 PM, Phillip Lord
<phillip.lord@russet.org.uk> wrote:
> Jim Meyering <jim@meyering.net> writes:
>
>> On Wed, May 18, 2016 at 2:15 AM, Phillip Lord
>> <phillip.lord@russet.org.uk> wrote:
>>> Yeah, I was adding two undo-boundaries to rather than just one. For no
>>> readily apparent reason I was directly changing the buffer-undo-list,
>>> rather than calling undo-boundary.
>>>
>>> Anyway, that should be fixed.
>>
>> Confirmed.
>> Thanks again for fixing all of that.
>
>
> Let me know if you find anything else.
>
> John, this is a reasonably extensive change now -- affecting both
> simple.el, but also a big rework of viper undo.
>
> To Emacs-25 or not to Emacs-25 that is the question?

Perspective of a viper-mode user: including this fix in Emacs-25 is a
must: without it, any existing viper-mode user will very quickly
notice how "undo" appears to destroy data, seemingly unrecoverably,
since "redo" does not restore it -- they'd have to go look in emacs'
yank buffer.