Update nix pin with make nixpkgs

Signed-off-by: Wong Hoi Sing Edison <hswong3i@gmail.com>

.cirrus.yml

@@ -775,11 +775,11 @@ static_build_task:
 
     build_script: |
         set -ex
-        mkdir -p /nix
         mkdir -p .cache
-        mount --bind .cache /nix
+        mv .cache /nix
         if [[ -z $(ls -A /nix) ]]; then podman run --rm --privileged -ti -v /:/mnt nixos/nix cp -rfT /nix /mnt/nix; fi
         podman run --rm --privileged -ti -v /nix:/nix -v ${PWD}:${PWD} -w ${PWD} nixos/nix nix --print-build-logs --option cores 8 --option max-jobs 8 build --file nix/
+        mv /nix .cache
         chown -Rf $(whoami) .cache
 
     binaries_artifacts:

nix/nixpkgs.json

@@ -1,7 +1,7 @@
 {
   "url": "https://github.com/nixos/nixpkgs",
-  "rev": "d6a445fe821052861b379d9b6c02d21623c25464",
-  "date": "2020-08-11T04:28:16+01:00",
-  "sha256": "064scwaxg8qg4xbmq07hag57saa4bhsb4pgg5h5vfs4nhhwvchg9",
+  "rev": "5f212d693fe1c82f9c7e20cd57bc69802b36a321",
+  "date": "2020-08-22T01:42:23+02:00",
+  "sha256": "1h3819ppllcpw07j884bjh07sma07vrrk1md92sf93cg43nmzncf",
   "fetchSubmodules": false
 }