[NixOS] Use gnupg 2_4_0 to avoid hanging emacs in loop when writing

nixos/base.nix

@@ -21,7 +21,13 @@
   systemd.services.systemd-user-sessions.enable = false;
 
   # Security
-  programs.gnupg.agent = { enable = true; enableSSHSupport = true; };
+  programs.gnupg = {
+    agent = {
+      enable = true;
+      enableSSHSupport = true;
+    };
+    package = pkgs.gnupg_2_4_0;
+  };
   services.pcscd.enable = true;
 
   # Networking

nixos/home-manager.nix

@@ -17,12 +17,14 @@ inputs: { pkgs, config, ... }: {
     enable = true;
   };
 
+  programs.gpg.package = pkgs.gnupg_2_4_0;
+
   services.gpg-agent = {
     enable = true;
     defaultCacheTtl = 8 * 60 * 60;
     maxCacheTtl = 8 * 60 * 60;
     enableSshSupport = true;
-    pinentryFlavor = "qt";
+    pinentryFlavor = "gnome3";
   };
 
   services.blueman-applet = {

nixos/overlay.nix

@@ -23,4 +23,14 @@ final: prev: {
       hash = "sha256-v0rr1s32jj79A8IGfJgSGJVlz7rSnZYn4ealOpqee0w=";
     };
   });
+
+  gnupg_2_4_0 = prev.gnupg.overrideAttrs(_: rec {
+    pname = "gnupg";
+    # 2.4.1 breaks emacs
+    version = "2.4.0";
+    src = prev.fetchurl {
+      url = "mirror://gnupg/gnupg/${pname}-${version}.tar.bz2";
+      hash = "sha256-HXkVjdAdmSQx3S4/rLif2slxJ/iXhOosthDGAPsMFIM=";
+    };
+  });
 }