Description:
------------
This is actually is a followup of #77308, because following up already closed bug is meaningless.

Still present in 7.3.3

Some details of test run:

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1. Versions (tried both ZTS and NTS, same results)

#/opt/php71/bin/php -v
PHP 7.1.27 (cli) (built: Mar 18 2019 13:00:22) ( ZTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.1.0, Copyright (c) 1998-2018 Zend Technologies

# /opt/php72/bin/php -v
PHP 7.2.16 (cli) (built: Mar 18 2019 13:03:57) ( ZTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.2.0, Copyright (c) 1998-2018 Zend Technologies

# /opt/php73/bin/php -v
PHP 7.3.3 (cli) (built: Mar 18 2019 13:07:58) ( ZTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.3.3, Copyright (c) 1998-2018 Zend Technologies

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2. Top data for ~10 sec of script run

7.1: 112241 root      20   0  307892  13932   8396 R 100.0  0.2   0:11.82 /opt/php71/bin/php ./test.php

7.2: 111796 root      20   0  310480  14228   8460 R  99.7  0.2   0:10.41 /opt/php72/bin/php ./test.php

7.3: 110517 root      20   0 1148804 848480   8716 R  99.7 10.4   0:10.37 /opt/php73/bin/php ./test.php

You can easily see RES size growing from stable 14M on PHP 7.1/7.2 to 840M+ on PHP 7.3. The script fails with out of memory error eventually (Allowed memory size of 1073741824 bytes exhausted (tried to allocate 16384 bytes) in /config/scripts/test.php on line 10)

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3. Script excerpt (it's ultimately simple, but the query returns 11+ million rows) is provided as 'Test script'

Test script:
---------------
#!/opt/php73/bin/php
<?php

error_reporting(E_ALL);
ini_set('display_errors', 1);
ini_set('memory_limit', '1G');

$db = new MySQLi('<server>', '<login>', '<password>', 'radius');
$res = $db->query('SELECT `AcctSessionId` AS `sid`, `AcctUniqueId` AS `uid` FROM `radacct` ORDER BY `AcctSessionId`, `AcctUniqueId`', MYSQLI_USE_RESULT);
while (is_array($row = $res->fetch_assoc()));
$res->free();

Expected result:
----------------
Memory does not leak

Actual result:
--------------
Memory leaks