make-disk-image: use nocache for smaller memory footprint

Author: Lassulus

lib/make-disk-image.nix

@@ -95,6 +95,7 @@ let
       util-linux
       findutils
       kmod
+      nocache
     ]
     ++ cfg.extraDependencies;
   preVM = ''
@@ -165,7 +166,7 @@ let
           P=${toString cfg.copyNixStoreThreads}
         ''
     }
-    xargs -P "$P" -I {} cp --recursive {} "$rootMountPoint"/nix/store < ${closureInfo}/store-paths
+    xargs -P "$P" -I {} nocache cp --recursive {} "$rootMountPoint"/nix/store < ${closureInfo}/store-paths
 
     ${systemToInstall.config.system.build.nixos-install}/bin/nixos-install --root "$rootMountPoint" --system ${systemToInstall.config.system.build.toplevel} --keep-going --no-channel-copy -v --no-root-password --option binary-caches ""
     umount -Rv "$rootMountPoint"