nixfmt-rfc-style

There is nothing in this commit except for the changes made by
nix-shell -p nixfmt-rfc-style --run "nixfmt ."

If this has mucked up your open branches then sorry about that. You
can probably nixfmt them to match before merging

pkgs/preinit/shell.nix

@@ -1,4 +1,4 @@
-with import <nixpkgs> {};
+with import <nixpkgs> { };
 mkShell {
   name = "preinit-env";
   src = ./.;