this derivation will be built:
  /nix/store/z7cik879k5anxrmsrhkrxmy8hagqcpix-nix-shell.drv
building '/nix/store/z7cik879k5anxrmsrhkrxmy8hagqcpix-nix-shell.drv'
building '/nix/store/z7cik879k5anxrmsrhkrxmy8hagqcpix-nix-shell.drv'
nix-shell> Running phase: buildPhase