bug#46915: [PATCH] Remove unecessary change_req arg from overlays_at()

[Eli Zaretskii <eliz@gnu.org>]

> From: Matt Armstrong <matt@rfc20.org>
> Cc: 46915@debbugs.gnu.org
> Date: Sat, 06 Mar 2021 16:03:14 -0800
> 
> > So I urge you to continue the work on the noverlay branch, and if that
> > branch will come with this and other changes in the internal APIs,
> > that's fine by me.  My problem is only with installing API changes
> > right now, when we are not at all sure yet the overlays redesign will
> > indeed land any time soon.
> >
> > OK?
> 
> I'm happy to defer this for now.

Thank you.  And thanks for your interest to this area in Emacs, whose
reimplementation is long overdue.

> I might come back and ask that this change go in before doing actual
> surgery on the overlay implementation.  In the past, on other projects,
> I have found it worthwhile to first simplify APIs, and assert various
> assumed invariants more rigidly, and let those changes bake for a while,
> before beginning to modify implementations.  But, I would agree that
> those kinds of changes are best done according to some sort of generally
> agreed upon plan, not just ad hoc.

If you do the work on a feature branch, the order is entirely up to
you.  What I'd like to avoid is to have such changes land on master
without being sure they will be reasonably closely followed by "the
real thing".  We had our share of disappointments with such changes in
the past, and I'd like to avoid repeating such mistakes.