To reproduce: ```bash nix build \ --impure \ --expr \ "with import <nixpkgs> {}; runCommandWith { name = ''hello-qemu''; runLocal = true; derivationArgs = { nativeBuildInputs = [ops]; NIX_DEBUG = 7;}; } ''ops build ${hello}/bin/hello''" ``` Log: ``` ... ++ ops build /bin/hello version lookup failed, using local. No local build found. + exitHandler + exitCode=1 + set +e + '[' -n '' ']' + (( 1 != 0 )) + runHook failureHook ... ``` The reason is apparently because `ops` tries to access the network which is prohibited in the `stdenv`.