Co-authored-by: FlafyDev <flafyarazi@gmail.com>
The dependency fixed-output derivation now uses the recursive hash mode to avoid tarballing and copying all the files.
https://github.com/NixOS/nix/issues/6660 was ran into during the development of this change. Input references were found in the Git package cache before nukeReferences was used.
It turns out that the mirrors in the Git package cache do not actually need to be preserved, as the SDK does not use them during the build process. They are therefore deleted in the dependency derivation and re-created as blank repositories in the main derivation.
A description of the Git package cache layout can be found here: c890afa1d6/lib/src/source/git.dart (L339)
Files and directories such as .dart_tool, .flutter-plugins, .packages and .pub-cache/hosted/*/.cache will be happily regenerated by the SDK in an offline environment.
The patches being made to these files and directories to remove non-determinism were flawed: They did not handle cases where files only appeared in one run, or cases where tooling versions had an effect on the output.
