these 4 derivations will be built:
  /nix/store/2adkxcbhbh56cs684ksxih9c4fbinjgn-cargo-nix-plugin-mirror-test-https-custom-ca.drv
  /nix/store/fqcng0qlw4man8661rhgaq52h2jsa4g5-cargo-nix-plugin-mirror-test-env-var.drv
  /nix/store/hh693ndix61zsdsjaiwd5hxv9m1lrbpr-cargo-nix-plugin-mirror-test-cargo-config.drv
  /nix/store/4yvis77xqzwspri3sbfarhh7nrz5fzsf-cargo-nix-plugin-mirror-tests.drv
building '/nix/store/hh693ndix61zsdsjaiwd5hxv9m1lrbpr-cargo-nix-plugin-mirror-test-cargo-config.drv' on 'ssh-ng://nix@jamie'
building '/nix/store/fqcng0qlw4man8661rhgaq52h2jsa4g5-cargo-nix-plugin-mirror-test-env-var.drv' on 'ssh-ng://nix@jamie'
building '/nix/store/2adkxcbhbh56cs684ksxih9c4fbinjgn-cargo-nix-plugin-mirror-test-https-custom-ca.drv' on 'ssh-ng://nix@jamie'