Add -H to sudo nix-env [...] to deal with warning

After NixOS/nix#6676, the following warning is displayed when running
`darwin-rebuild switch`:
  warning: $HOME ('/Users/jamie') is not owned by you, falling back to the
  one defined in the 'passwd' file.

pkgs/nix-tools/darwin-rebuild.sh

@@ -160,7 +160,7 @@ fi
 
 if [ "$action" = list ] || [ "$action" = rollback ]; then
   if [ "$USER" != root ] && [ ! -w $(dirname "$profile") ]; then
-    sudo nix-env -p "$profile" "${extraProfileFlags[@]}"
+    sudo -H nix-env -p "$profile" "${extraProfileFlags[@]}"
   else
     nix-env -p "$profile" "${extraProfileFlags[@]}"
   fi
@@ -178,7 +178,7 @@ if [ -z "$systemConfig" ]; then exit 0; fi
 
 if [ "$action" = switch ]; then
   if [ "$USER" != root ] && [ ! -w $(dirname "$profile") ]; then
-    sudo nix-env -p "$profile" --set "$systemConfig"
+    sudo -H nix-env -p "$profile" --set "$systemConfig"
   else
     nix-env -p "$profile" --set "$systemConfig"
   fi