Add all default NixOS packages to the channel

The job ‘dummy’ depends on the default contents of
‘environment.systemPackages’, thus ensuring that those packages all
end up in the channel.

nixos/release-combined.nix

···
+# This jobset defines the main NixOS channels (such as nixos-unstable
+# and nixos-14.04). The channel is updated every time the ‘tested’ job
+# succeeds, and all other jobs have finished (they may fail).
+
 { nixpkgs ? { outPath = ./..; revCount = 56789; shortRev = "gfedcba"; }
 , stableBranch ? false
 , supportedSystems ? [ "x86_64-linux" "i686-linux" ]
···
 in rec {
 
   nixos = removeMaintainers (import ./release.nix {
-    inherit stableBranch;
+    inherit stableBranch supportedSystems;
     nixpkgs = nixpkgsSrc;
   });
 
···
   tested = pkgs.releaseTools.aggregate {
     name = "nixos-${nixos.channel.version}";
     meta = {
-      description = "Release-critical builds for the NixOS unstable channel";
-      maintainers = [ pkgs.lib.maintainers.eelco pkgs.lib.maintainers.shlevy ];
+      description = "Release-critical builds for the NixOS channel";
+      maintainers = [ pkgs.lib.maintainers.eelco ];
     };
     constituents =
-      let all = x: map (p: x.${p}) supportedSystems; in
+      let all = x: map (system: x.${system}) supportedSystems; in
       [ nixos.channel
+        (all nixos.dummy)
         (all nixos.manual)
 
         (all nixos.iso_minimal)

nixos/release.nix

···
   );
 
 
+  # Ensure that all packages used by the minimal NixOS config end up in the channel.
+  dummy = forAllSystems (system: pkgs.runCommand "dummy"
+    { propagatedBuildInputs = (import lib/eval-config.nix {
+        inherit system;
+        modules = lib.singleton ({ config, pkgs, ... }: { });
+      }).config.environment.systemPackages;
+    }
+    "mkdir $out; fixupPhase");
+
+
   # Provide a tarball that can be unpacked into an SD card, and easily
   # boot that system from uboot (like for the sheevaplug).
   # The pc variant helps preparing the expression for the system tarball