sg: add setuid wrapper. (newgrp is a symlink to sg and was already setuid).

sudo: add ability for wheel users to change group (as well as user)

nixos/modules/programs/shadow.nix

@@ -100,7 +100,7 @@ in
         chgpasswd = { rootOK = true; };
       };
 
-    security.setuidPrograms = [ "passwd" "chfn" "su" "newgrp"
+    security.setuidPrograms = [ "passwd" "chfn" "su" "sg" "newgrp"
       "newuidmap" "newgidmap"  # new in shadow 4.2.x
       ];
 

nixos/modules/security/sudo.nix

@@ -77,7 +77,7 @@ in
         root        ALL=(ALL) SETENV: ALL
 
         # Users in the "wheel" group can do anything.
-        %wheel      ALL=(ALL) ${if cfg.wheelNeedsPassword then "" else "NOPASSWD: ALL, "}SETENV: ALL
+        %wheel      ALL=(ALL:ALL) ${if cfg.wheelNeedsPassword then "" else "NOPASSWD: ALL, "}SETENV: ALL
         ${cfg.extraConfig}
       '';