stage-2-init: Use the host bash as SHELL

Changed files
+1
nixos
modules
system
+1
nixos/modules/system/boot/stage-2.nix
···
bootStage2 = pkgs.substituteAll {
src = ./stage-2-init.sh;
shellDebug = "${pkgs.bashInteractive}/bin/bash";
+
shell = "${pkgs.bash}/bin/bash";
isExecutable = true;
inherit (config.nix) readOnlyStore;
inherit (config.networking) useHostResolvConf;