this derivation will be built:
  /nix/store/gjgwc6cihhgnc7jkic57xwsvl1xfcj02-nix-shell.drv
building '/nix/store/gjgwc6cihhgnc7jkic57xwsvl1xfcj02-nix-shell.drv' on 'grpc://farm.numtide.com:50051?connect-timeout=20&system=aarch64-linux&token-file=/run/nix-farm-client/farm-token'
building '/nix/store/gjgwc6cihhgnc7jkic57xwsvl1xfcj02-nix-shell.drv' on farm.numtide.com:50051
nix-shell> elastic-arm-9a50e053: building gjgwc6cihhgnc7jkic57xwsvl1xfcj02-nix-shell.drv
nix-shell> Running phase: buildPhase