bug#55149: 29.0.50; Commit f30625943e broke magit/with-editor

[Juri Linkov]

>> The regression is that the return value of :after now overrides
>> the return value of the original function.
>
> Oh, indeed.  But isn't that exactly as documented for add-function?
>
>  :after (lambda (&rest r) (apply OLDFUN r) (apply FUNCTION r))

Indeed, it seems documentation differed from the actual implementation.

> Of course, we'd rather want
>
>  :after (lambda (&rest r) (prog1 (apply OLDFUN r) (apply FUNCTION r)))

Yep, this looks like what it's natural to expect from such advice type.
Or maybe a new type could be added to modify the return value?