nixUnstable: pre20220124 -> pre20220127

fixes https://github.com/NixOS/nix/issues/5998
and https://github.com/NixOS/nix/issues/5980

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

@@ -9,6 +9,7 @@ assert (sha256 == null) -> (src != null);
 let
   atLeast24 = lib.versionAtLeast version "2.4pre";
   atLeast25 = lib.versionAtLeast version "2.5pre";
+  atLeast27 = lib.versionAtLeast version "2.7pre";
 in
 { stdenv
 , autoconf-archive
@@ -100,6 +101,8 @@ stdenv.mkDerivation {
     lowdown
   ] ++ lib.optionals (atLeast24 && stdenv.isx86_64) [
     libcpuid
+  ] ++ lib.optional (atLeast27) [
+    nlohmann_json
   ] ++ lib.optionals withLibseccomp [
     libseccomp
   ] ++ lib.optionals withAWS [

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

@@ -67,12 +67,12 @@ in lib.makeExtensible (self: {
 
   unstable = lib.lowPrio (common rec {
     version = "2.7";
-    suffix = "pre20220124_${lib.substring 0 7 src.rev}";
+    suffix = "pre20220127_${lib.substring 0 7 src.rev}";
     src = fetchFromGitHub {
       owner = "NixOS";
       repo = "nix";
-      rev = "0a70b37b5694c769fb855c1afe7642407d1db64f";
-      sha256 = "sha256-aOM9MPNlnWNMobx4CuD4JIXH2poRlG8AKkuxY7FysWg=";
+      rev = "558c4ee3e370c9f9a6ea293df54ed6914a999f1c";
+      sha256 = "sha256-hMzKQflpgf3P7OdYKSnD1VMBSnF48XSRjaNX3bUJct4=";
     };
   });
 })