these 2 derivations will be built:
  /nix/store/5sl77c9h331kcfp79bianns2hcz879p7-flake-update.json.drv
  /nix/store/2j1iwssrch2sfwsky742bwvh2vgjsxv2-inputDerivation-flake-update.drv
building '/nix/store/5sl77c9h331kcfp79bianns2hcz879p7-flake-update.json.drv'...
building '/nix/store/2j1iwssrch2sfwsky742bwvh2vgjsxv2-inputDerivation-flake-update.drv'...