php 7.0.12 stream with fopen url error

test.php

<?php

ini_set('display_errors', 'on');

// Example class : http://php.net/manual/en/function.stream-filter-register.php#example-4575
class strtoupper_filter extends php_user_filter {
  function filter($in, $out, &$consumed, $closing)
  {
    while ($bucket = stream_bucket_make_writeable($in)) {
      $bucket->data = strtoupper($bucket->data);
      $consumed += $bucket->datalen;
      stream_bucket_append($out, $bucket);
    }
    return PSFS_PASS_ON;
  }
}

stream_filter_register('strtoupper', 'strtoupper_filter');

#$fp = fopen(__DIR__ . '/test.txt', 'r'); # WORKS
$fp = fopen('http://localhost/test.txt', 'r'); # DOES NOT WORK

stream_filter_append($fp, 'strtoupper', STREAM_FILTER_READ); # DOES NOT WORK
#stream_filter_append($fp, 'string.toupper', STREAM_FILTER_READ); # WORKS

fpassthru($fp);
fclose($fp);

test.txt

This is a text file.