Description:
------------
Looks like references behavior has changed in 7.x comparing to 5.5.
First of all, once variable becomes reference, it never looses that flag, even though the second reference is already destroyed (see the first function "create_references").
Second, I'm able to change the original variable by passing its copy to a function and modifying it there, which is definitely counter-intuitive.
I expected the function to copy the variable to write, since it was not passed by reference, as that's what seems to be happening in PHP 5.5

Test script:
---------------
/* after this function all array elements become references */
function create_references(&$array) {
    $refs[] = &$array;
    foreach ($array as $key => $value) {
        create_references($array[$key]);
    }
}   

/* a copy is passed and then modified, which also modifies the original variable */
function change_copy($copy) {
    for ($i = 0; $i < 2; $i++) {
        $copy['b']['b'] = $copy['b']; //this causes recursion
    }
}   

$data = [
    'a' => [
        'b' => [],
    ],  
];  
 
create_references($data);
 
$copy = $data['a'];
var_dump($data);

change_copy($copy);
var_dump($data); //RECURSION

Expected result:
----------------
array(1) {
  ["a"]=>
  array(1) {
    ["b"]=>
    array(0) {
    }
  }
}
array(1) {
  ["a"]=>
  array(1) {
    ["b"]=>
    array(0) {
    }
  }
}


Actual result:
--------------
array(1) {
  ["a"]=>
  array(1) {
    ["b"]=>
    array(0) {
    }
  }
}
array(1) {
  ["a"]=>
  array(1) {
    ["b"]=>
    array(1) {
      ["b"]=>
      *RECURSION*
    }
  }
}