* Adapted nix-pull to use the new substitute mechanism.

corepkgs/nix-pull/builder.sh.in

@@ -0,0 +1,34 @@
+#! @shell@ -e
+
+export PATH=/bin:/usr/bin
+
+mkdir $out
+
+cat > $out/fetch <<EOF
+#! @shell@ -e
+
+export PATH=/bin:/usr/bin
+
+echo "downloading \$2..."
+
+export PRINT_PATH=1
+result=(\$(@bindir@/nix-prefetch-url \$2))
+
+hash=\${result[0]}
+path=\${result[1]}
+
+if test "\$hash" != "\$3"; then
+    echo "hash is \$hash, expected \$3"
+    exit 1
+fi
+
+echo "unpacking into \$1..."
+
+if ! @bunzip2@ < "\$path" | @bindir@/nix-store --restore "\$1"; then
+    exit 1
+fi
+
+exit 0
+EOF
+
+chmod +x $out/fetch