Added nix-reduce-build. You point it to some path you want to build and it fetches whatever it can from specified computers via nix-copy-closure. NOTE: You do want to set up RSA keys or ssh-agent or something... You really do want it. It will run separate ssh instances insane number of times.

scripts/Makefile.am

@@ -2,7 +2,7 @@ bin_SCRIPTS = nix-collect-garbage \
   nix-pull nix-push nix-prefetch-url \
   nix-install-package nix-channel nix-build \
   nix-pack-closure nix-unpack-closure \
-  nix-copy-closure
+  nix-copy-closure nix-reduce-build
 
 noinst_SCRIPTS = nix-profile.sh generate-patches.pl \
   find-runtime-roots.pl build-remote.pl
@@ -35,4 +35,5 @@ EXTRA_DIST = nix-collect-garbage.in \
   nix-pack-closure.in nix-unpack-closure.in \
   nix-copy-closure.in \
   find-runtime-roots.pl.in \
-  build-remote.pl.in
+  build-remote.pl.in \
+  nix-reduce-build.in