wfvm.nix: turn wfvm-pkgs into an arg with default

artiq-fast/conda-windows/binutils.nix

@@ -1,7 +1,10 @@
 { pkgs, version, src, target }:
 
 let
-  wfvm = import ../wfvm.nix { inherit pkgs; };
+  wfvm = import ../wfvm.nix {
+    inherit pkgs;
+    wfvm-pkgs = pkgs;
+  };
   libiconv-filename = "libiconv-1.15-h1df5818_7.tar.bz2";
   libiconv = pkgs.fetchurl {
     url = "https://anaconda.org/anaconda/libiconv/1.15/download/win-64/${libiconv-filename}";

artiq-fast/conda-windows/llvm-or1k.nix

@@ -1,7 +1,10 @@
 { pkgs, version, src }:
 
 let
-  wfvm = import ../wfvm.nix { inherit pkgs; };
+  wfvm = import ../wfvm.nix {
+    inherit pkgs;
+    wfvm-pkgs = pkgs;
+  };
   conda-vs2015_runtime-filename = "vs2015_runtime-14.16.27012-hf0eaf9b_2.tar.bz2";
   conda-vs2015_runtime = pkgs.fetchurl {
     url = "https://anaconda.org/anaconda/vs2015_runtime/14.16.27012/download/win-64/${conda-vs2015_runtime-filename}";

artiq-fast/conda-windows/llvmlite-artiq.nix

@@ -1,7 +1,10 @@
 { pkgs, conda-windows-llvm-or1k, version, src }:
 
 let
-  wfvm = import ../wfvm.nix { inherit pkgs; };
+  wfvm = import ../wfvm.nix {
+    inherit pkgs;
+    wfvm-pkgs = pkgs;
+  };
   conda-vs2015_runtime-filename = "vs2015_runtime-14.16.27012-hf0eaf9b_2.tar.bz2";
   conda-vs2015_runtime = pkgs.fetchurl {
     url = "https://anaconda.org/anaconda/vs2015_runtime/14.16.27012/download/win-64/${conda-vs2015_runtime-filename}";

artiq-fast/wfvm.nix

@@ -1,16 +1,16 @@
-{ pkgs }:
-
-let
-  # Pin nixpkgs to avoid frequent resource-intensive Windows reinstallations on Hydra.
-  wfvm-pkgs = pkgs.fetchFromGitHub {
+{ pkgs
+, wfvm-pkgs ? import (pkgs.fetchFromGitHub {
     owner = "NixOS";
     repo = "nixpkgs";
     rev = "f8248ab6d9e69ea9c07950d73d48807ec595e923";
     sha256 = "009i9j6mbq6i481088jllblgdnci105b2q4mscprdawg3knlyahk";
-  };
+  }) {}
+}:
+
+let
   wfvm = pkgs.fetchgit {
     url = "https://git.m-labs.hk/M-Labs/wfvm.git";
     rev = "4b497938ffd9fcddf84a3dbe2f01524395292adb";
     sha256 = "0m3kdbbcskqc1lf8b5f7ccbll9b7vkl4r00kbyx3yjb2rs6cqvil";
   };
-in import "${wfvm}/wfvm" { pkgs = (import wfvm-pkgs {}); }
+in import "${wfvm}/wfvm" { pkgs = wfvm-pkgs; }

artiq-fast/windows/make_conda_packages.sh

@@ -13,7 +13,10 @@ set -e
 nix-build -E "
 let
   pkgs = import <nixpkgs> {};
-  wfvm = import ../wfvm.nix { inherit pkgs; };
+  wfvm = import ../wfvm.nix {
+    inherit pkgs;
+    wfvm-pkgs = pkgs;
+  };
 in
   wfvm.utils.wfvm-run {
     name = \"get-conda-packages\";

artiq-fast/windows/run-test.nix

@@ -10,7 +10,10 @@ let
       inherit port;
     }) tcpPorts;
 
-  wfvm = import ../wfvm.nix { inherit pkgs; };
+  wfvm = import ../wfvm.nix {
+    inherit pkgs;
+    wfvm-pkgs = pkgs;
+  };
   conda-deps = {
     name = "conda-deps";
     script = let