these 4 derivations will be built:
  /nix/store/kl09i5qp47qfw64lq6aq6h55cjgaa52g-source.drv
  /nix/store/bia5r2hr793dj0ws2niv443ihjkg52km-lean-ctx-3.9.20-vendor-staging.drv
  /nix/store/16k8wm6z21ggif3cr17xdgrlcclwgrcn-lean-ctx-3.9.20-vendor.drv
  /nix/store/i6nrcvh0l1ajg7vad46drqn3n1bgaqa7-lean-ctx-3.9.20.drv