Lorri does not use bashInteractive like nix-shell

[erikarvstedt]

Description
Lorri uses pkgs.bash instead of pkgs.bashInteractive like nix-shell, causing some shell derivations to fail.

Reproduce
Lorri fails when evaluating the following shell.nix.
Reason: shellHook uses the function compgen which is unavailable in noninteractive bash.

{ pkgs ? import <nixpkgs> {} }:

pkgs.mkShell {
 shellHook = ''
   compgen -e
 '';
}

Expected behavior
Lorri should support all shell derivations that work with nix-shell.

Details
I'm using compgen in nix-shells in the context of export -n $(compgen -e) to clear exports and reexport specific variables.

If lorri would use bashInteractive, the following workaround could be removed: #392