Eli Zaretskii <eliz@gnu.org> writes:

>> I think there's a case to be made for fixing this bug for Emacs 25.1.
>
> It depends on what the fix will look like.  If it's simple and safe
> enough, I'll agree.


The following patch addresses the issue in my hands. I'd welcome
confirmation.

Stefan what do you think? You suggested something like this for
Bug#22295 also. I think that the problem is the same; if I read
insert-file-contents correctly, it disables collection of undo
information. I may well be reading it wrong though.

Given that this has turned up in two places now, it may be a wider
problem, and the more general solution might be the better one. It might
also invalidate the necessity for 12e009e52, but I haven't tested that
yet.

Alternatively, revert-buffer could just force undo-boundary.

Phil