So that $ nix-build -A bcache-tools.src gives /nix/store/HASH-bcache-tools-1.0.7.tar.gz instead of /nix/store/HASH-v1.0.7.tar.gz
So that $ nix-build -A bcache-tools.src gives /nix/store/HASH-bcache-tools-1.0.7.tar.gz instead of /nix/store/HASH-v1.0.7.tar.gz