Use `//i` for case-insensitivity?

Both replaces can be fixed like so:

```
> v = "Linux foo Linux foo GNU/Linux foo GNU/Linux"
"Linux foo Linux foo GNU/Linux foo GNU/Linux"
> v.replace(/(GNU\/)?linux/ig, function($0,$1){ return $1?$0:'GNU/Linux';});
"GNU/Linux foo GNU/Linux foo GNU/Linux foo GNU/Linux"
```