pull swarm closures through the nix daemon: substituters in the fragment, merged root-only netrc

nix/script-tests/cache-pull-substitute.nix

@@ -0,0 +1,18 @@
+# `checks.script-test-cache-pull-substitute` — runs the closure pull
+# (`nix-store --realise <top> --max-jobs 0`, hive-c0re/src/cache_pull.rs)
+# against two file caches: a swarm cache that has the top path and lacks a
+# dependency, and the host's own substituter that has the dependency. The cases
+# are in ./cache-pull-substitute.sh.
+{ pkgs, ... }:
+pkgs.runCommand "hyperhive-script-test-cache-pull-substitute"
+  {
+    nativeBuildInputs = [
+      pkgs.nix
+      pkgs.coreutils
+      pkgs.gnugrep
+    ];
+  }
+  ''
+    ${pkgs.bash}/bin/bash ${./cache-pull-substitute.sh}
+    touch "$out"
+  ''