Merge #4661

4661: fix pure nix evaluation r=dermetfan a=dermetfan

There was access to `builtin.currentSystem` in the nix evaluation for nix-shell so pure evaluation was not possible.

Needed by cardano-scaling/hydra#625.

Co-authored-by: Robin Stumm <[email protected]>

Author: iohk-bors[bot]

default.nix

@@ -13,8 +13,9 @@ in
       inherit profileName workbenchDevMode;
     };
   }
+, system ? builtins.currentSystem
 }:
 with (import ./nix/flake-compat.nix customConfig);
-defaultNix // defaultNix.packages.${builtins.currentSystem} // {
-  private.project = defaultNix.legacyPackages.${builtins.currentSystem};
+defaultNix // defaultNix.packages.${system} // {
+  private.project = defaultNix.legacyPackages.${system};
 }