nixos-enter: Check whether --root denotes a NixOS installation

Changed files
+5
nixos
modules
installer
+5
nixos/modules/installer/tools/nixos-enter.sh
···
esac
done
+
if [[ ! -e $mountPoint/etc/NIXOS ]]; then
+
echo "$0: '$mountPoint' is not a NixOS installation" >&2
+
exit 126
+
fi
+
mkdir -m 0755 -p "$mountPoint/dev"
mount --rbind /dev "$mountPoint/dev"