b8a19ca2bc
There are two use case for this flag: 1. NixOS developer usually use a nixpkgs checkout for development. Copying nixpkgs everytime when rebuilding NixOS is way to slow, even with NVME disks. 2. Folks migrating from impure configuration in a sufficient complex infrastructure need this flag to gradually migrate to NixOS flakes.
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at https://nixos.org/nixos and in the manual in doc/manual.