Re: master 19a3b499f84: ; * lisp/loadup.el: Don't prohibit advice when ls-lisp is loaded.

[Stefan Monnier <monnier@iro.umontreal.ca>]

>> IOW, merge `insert-directory` and `ls-lisp--insert-directory`
>> by allowing `insert-directory-program` to be nil
>> (as a replacement for the `ls-lisp-use-insert-directory-program`
>> boolean) in which case we use the ls-lisp code?
>
> So if some Lisp program out there sets insert-directory-program to a
> non-nil value (probably intending to affect only Posix systems), Emacs
> on MS-Windows will suddenly start using it instead of ls-lisp?
>
> In general, IMO it's too late to make changes in this arrangement that
> would require users to switch to customizing a different user option.

Then we can change the code to keep the same config vars but to change
`insert-directory` so it tests `ls-lisp-use-insert-directory-program`
and delegates to `ls-lisp` if non-nil, IOW hardcode the effect of
the advice.


        Stefan