these 4 derivations will be built:
  /nix/store/l56v88dfm3mk3kbdrarl09f934rkfqz8-source.drv
  /nix/store/rchax1c4y0mcgigjhb9k6h1m1dk40n4n-lean-ctx-3.9.19-vendor-staging.drv
  /nix/store/dfa9913si8km82hp4aykpawbrcvswscr-lean-ctx-3.9.19-vendor.drv
  /nix/store/rmzll8hpib8wswrwcgafga29ga0vhlc6-lean-ctx-3.9.19.drv