Description:
------------
phpdbg loads files but does not discard the file handles.
When trying to use phpdbg -qrr to generate code coverage reports for phpunit, the system max open files limit is reached very quickly.

This does not happen with xdebug at all and essentially makes phpdbg useless for code coverage generation on a larger project

Test script:
---------------
touch empty.php

echo '<?php

for ($i = 0; $i < 25000; $i++)
{
    require("empty.php");
}' > test.php

phpdbg -qqr test.php

Expected result:
----------------
Same as xdebug - the run to finish without error

Actual result:
--------------
2096 phpdbg:master> phpdbg -qrr test.php
[PHP Warning:  require(empty.php): failed to open stream: Too many open files in /Users/nicols/git/tmp/phpdbg/test.php on line 5]
[PHP Warning:  require(empty.php): failed to open stream: Too many open files in /Users/nicols/git/tmp/phpdbg/test.php on line 5]
[PHP Fatal error:  require(): Failed opening required 'empty.php' (include_path='.:/usr/local/Cellar/php/7.2.10/share/php/pear') in /Users/nicols/git/tmp/phpdbg/test.php on line 5]