Welcome! This nixpkgs fork is where I stage my public contributions to upstream NixOS/nixpkgs. I'm currently working on packaging the Xen Hypervisor; check the branches for sources. Everything is targeting the master branch in upstream nixpkgs.
Please avoid opening issues or PRs here; report them to upstream NixOS/nixpkgs instead. I only use GitHub for upstream contributions, so I might not see your comments to this repository.
Nixpkgs is licensed under the MIT License.
Note: MIT license does not apply to the packages built by Nixpkgs, merely to the files in this repository (the Nix expressions, build scripts, NixOS modules, etc.). It also might not apply to patches included in Nixpkgs, which may be derivative works of the packages to which they apply. The aforementioned artifacts are all covered by the licenses of the respective packages.