Accidentally removed in ca96f52194. This
caused `nix run` to systematically fail with
```
error: app program '/nix/store/…' is not in the Nix store
```
'nix run' will try to run $out/bin/<name>, where <name> is the
derivation name (excluding the version). This often works well:
$ nix run nixpkgs#hello
Hello, world!
$ nix run nix -- --version
nix (Nix) 2.4pre20200626_adf2fbb
$ nix run patchelf -- --version
patchelf 0.11.20200623.e61654b
$ nix run nixpkgs#firefox -- --version
Mozilla Firefox 77.0.1
$ nix run nixpkgs#gimp -- --version
GNU Image Manipulation Program version 2.10.14
though not always:
$ nix run nixpkgs#git
error: unable to execute '/nix/store/kp7wp760l4gryq9s36x481b2x4rfklcy-git-2.25.4/bin/git-minimal': No such file or directory