Description:
------------
for some reason using argon2i as a hash algorithm, it always dumps out a NUL byte at the end which doesnt happen with bcrypt.


I just use the PHP7.2-RC2 x64-nts from windows.php.net on a webserver using cgi

Test script:
---------------
<?php
header("Content-type: text/plain");
$pwhash=password_hash("php",PASSWORD_ARGON2I,[
  'memory_cost' => 16384, // 16 Mb
  'time_cost'   => 2,
  'threads'     => 4,]);
  
  
echo  $pwhash;

$pwhash2=password_hash("php",PASSWORD_BCRYPT,[
  "cost"=> 10]);
  echo PHP_EOL.PHP_EOL;
  echo $pwhash2;

Expected result:
----------------
that it wont dump a NUL at the end

Actual result:
--------------
it does throw a NUL byte at the end.