> var_dump($wgAutopromote)
array(5) {
  ["autoconfirmed"]=>
  array(3) {
    [0]=>
    string(1) "&"
    [1]=>
    array(2) {
      [0]=>
      int(1)
      [1]=>
      int(10)
    }
    [2]=>
    array(2) {
      [0]=>
      int(2)
      [1]=>
      int(345600)
    }
  }
  ["checkuser"]=>
  array(0) {
  }
  ["interwiki-admin"]=>
  array(0) {
  }
  ["oversight"]=>
  array(0) {
  }
  ["steward"]=>
  array(0) {
  }
}


vs it being set

> var_dump($wgAutopromote)
array(6) {
  ["autoconfirmed"]=>
  array(3) {
    [0]=>
    string(1) "&"
    [1]=>
    array(2) {
      [0]=>
      int(1)
      [1]=>
      int(10)
    }
    [2]=>
    array(2) {
      [0]=>
      int(2)
      [1]=>
      int(345600)
    }
  }
  ["user"]=>
  array(3) {
    [0]=>
    string(1) "!"
    [1]=>
    int(8)
    [2]=>
    int(9)
  }
  ["checkuser"]=>
  array(0) {
  }
  ["interwiki-admin"]=>
  array(0) {
  }
  ["oversight"]=>
  array(0) {
  }
  ["steward"]=>
  array(0) {
  }
}