It is a plain emacs built with nixos. These packages are just different versions of emacs, like stable/unstable/master and with or without native compilation/pgtk. Also it contains all elpa/melpa packages and functions to install them in nixos.

On Fri, Jan 21, 2022 at 9:26 AM Lars Ingebrigtsen <larsi@gnus.org> wrote:
Евгений Курневский <kurnevsky@gmail.com> writes:

> Just a repository with additional emacs packages:
> https://github.com/nix-community/emacs-overlay
> Overlay is a nixos term: https://nixos.wiki/wiki/Overlays

So the problem could be in these packages?  Could you try to build a
plain emacs-28 and see whether you can reproduce the problems there?

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   bloggy blog: http://lars.ingebrigtsen.no


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С уважением, Курневский Евгений.