these 4 derivations will be built:
  /nix/store/08hfy28ywzlnh14j2h4j1l6725k7klyx-Cargo.toml.drv
  /nix/store/763h8fwwx3xwna0grkshzg1ydn8746l6-source.drv
  /nix/store/l2w1r2a70cywlnmbllafjcm5p4j64sax-harmonia-deps-3.1.0.drv
  /nix/store/zzhwkkqz8apib04b7h18pf76j1ybvrca-harmonia-llvm-cov-3.1.0.drv
Failed to find a machine for remote build!
derivation: l2w1r2a70cywlnmbllafjcm5p4j64sax-harmonia-deps-3.1.0.drv
required (system, features): (aarch64-linux, [])
1 available machines:
(systems, maxjobs, supportedFeatures, mandatoryFeatures)
([aarch64-darwin, x86_64-darwin], 8, [big-parallel, recursive-nix], [])
Failed to find a machine for remote build!
derivation: zzhwkkqz8apib04b7h18pf76j1ybvrca-harmonia-llvm-cov-3.1.0.drv
required (system, features): (aarch64-linux, [])
1 available machines:
(systems, maxjobs, supportedFeatures, mandatoryFeatures)
([aarch64-darwin, x86_64-darwin], 8, [big-parallel, recursive-nix], [])