+expected_env_command_RE='^nix-env --profile /path/to/profile --show-trace --file '\''<nix/unpack-channel.nix>'\'' --install -I pinch_tarball_for_(repo-[0-9]{10}-[0-9a-f]{11})=('"$NIX_STORE_DIR"'/.{32}-\1.tar.xz) --from-expression '\''f: f \{ name = "\1"; channelName = "foo"; src = builtins.storePath "\2"; \}'\''$'