
In 0945178b3c6fd9e33002dd6e3c6f77dfca49565a we decided that Perl-based VM tests should be deprecated and will be removed between 20.03 and 20.09. So let's switch `nixos-build-vms(8)` to python as well (which is entirely interactive, so other scripts won't break). In my experience, the test-driver isn't used most of the time, so this patch is mainly supposed to get rid of the (probably misleading) deprecation warning when running `nixos-build-vms`. Apart from that, the interface for python's test-driver is way nicer.
To build the manual, you need Nix installed on your system (no need for NixOS). To install Nix, follow the instructions at https://nixos.org/nix/download.html When you have Nix on your system, in the root directory of the project (i.e., `nixpkgs`), run: nix-build nixos/release.nix -A manual.x86_64-linux When this command successfully finishes, it will tell you where the manual got generated.