Prototype implementation of Nix store path rewriting as described in this issue.

Example

make
./pack $(nix-build '<nixpkgs>' -A firefox) firefox.cpio firefox.dep
./unpack /tmp/store firefox.cpio firefox.dep 

The firefox closure is now unpacked in /tmp/store with all paths rewritten accordingly. Be sure to rename /nix to something else before testing to avoid false positives.