bug#23906: 25.0.95; Undo boundary after process output is not consistent

[Phillip Lord]

Stefan Monnier <monnier@iro.umontreal.ca> writes:
>
> How 'bout the patch below (see the viper part to get an idea about how
> to use it in ediprolog)?

Looks good. Could do with a test or two! Changing the undo system was
made harder the absence of tests I think.

> +(viper-deflocalvar viper--undo-change-group-handle nil)
> +(put 'viper--undo-change-group-handle 'permanent-local t)

Why the permanent-local? This will remove undo boundaries even over an
major-mode change surely?

Phil