nixUnstable: 2.4pre20210802_47e96bb -> 2.4pre20210908_3c56f62

Main motivation for is the bugfix regarding flake-follows and
path-inputs[1]. An overview over all changes - mostly bugfixes -
can be found on GitHub[2].

[1] NixOS/nix#4641
[2] NixOS/nix@47e96bb...3c56f62

pkgs/tools/package-management/nix/default.nix

@@ -234,13 +234,13 @@ in rec {
   nixUnstable = lib.lowPrio (callPackage common rec {
     pname = "nix";
     version = "2.4${suffix}";
-    suffix = "pre20210802_47e96bb";
+    suffix = "pre20210908_${lib.substring 0 7 src.rev}";
 
     src = fetchFromGitHub {
       owner = "NixOS";
       repo = "nix";
-      rev = "47e96bb533f8cacc171bec9b688b134de31a48a9";
-      sha256 = "sha256-vwj1fAGn3Pl9Vr/qSL+oDxuwbRzEdI3dsEg6o3xTmWg=";
+      rev = "3c56f62093601143838af923195f630d8ffae2d4";
+      sha256 = "sha256-pjdzLOEt8i1NQe4drLpp8+LrRd2MgsISSQEsMebz2kc=";
     };
 
     boehmgc = boehmgc_nixUnstable;