Replace emacs 26 with 27

modules/editors/emacs.nix

@@ -7,7 +7,7 @@
   my = {
     packages = with pkgs; [
       ## Doom dependencies
-      emacs
+      my.emacs27
       git
       (ripgrep.override {withPCRE2 = true;})
 

overlays.nix

@@ -1,14 +1,15 @@
 [
   (self: super: with super; {
     my = {
-      linode-cli = (callPackage ./packages/linode-cli.nix {});
-      ripcord = (callPackage ./packages/ripcord.nix {});
-      zunit = (callPackage ./packages/zunit.nix {});
+      ant-dracula = (callPackage ./packages/ant-dracula.nix {});
       cached-nix-shell =
         (callPackage
           (builtins.fetchTarball
             https://github.com/xzfc/cached-nix-shell/archive/master.tar.gz) {});
-      ant-dracula = (callPackage ./packages/ant-dracula.nix {});
+      emacs27 = (callPackage ./packages/emacs27.nix {});
+      linode-cli = (callPackage ./packages/linode-cli.nix {});
+      ripcord = (callPackage ./packages/ripcord.nix {});
+      zunit = (callPackage ./packages/zunit.nix {});
     };
 
     nur = import (builtins.fetchTarball "https://github.com/nix-community/NUR/archive/master.tar.gz") {

packages/emacs27.nix

@@ -0,0 +1,19 @@
+# https://github.com/nix-community/emacs-overlay is all about Emacs HEAD and
+# pkgs.emacs is all about stable, but I want 27.0.90 with its native JSON
+# library, and none of HEAD's instability, so...
+
+{ stdenv, pkgs, lib, fetchurl, ... }:
+
+pkgs.emacsGit.overrideAttrs (oa: rec {
+  name = "emacs-${version}";
+  version = "27.0.90";
+  src = fetchurl {
+    url = "https://alpha.gnu.org/gnu/emacs/pretest/${name}.tar.xz";
+    sha256 = "1x0z9hfq7n88amd32714g9182nfy5dmz9br0pjqajgq82vjn9qxk";
+  };
+  buildInputs = oa.buildInputs ++ [ pkgs.jansson ];
+  configureFlags = oa.configureFlags ++ [ "--with-jansson" ];
+
+  # Remove tramp-detect-wrapped-gvfsd.patch because it doesn't work with 27.0.90
+  patches = lib.drop 1 oa.patches;
+})