these 2 derivations will be built:
  /nix/store/r8n2q5qisg1qx3hxsnsk2yy6mqjcqpxv-cargo-vendor-dir.drv
  /nix/store/4caf6mz0c2181qhbmijyicl1jlcg2in1-ssync-0.6.0.drv