[1.0] Can not edit keys with env() method as value

[Demacri]

Using Config::write on keys that have env('SOME_KEY','something') as value, it doesn't work.
Example:
'url' => env('APP_URL','http://localhost:83')
using
Config::write('app', ['url' => 'http://localhost:83']);
the result is

Unable to rewrite key "url" in config, rewrite failed