Wondering about "aweful hack" in PHPStorm's PHPUnit Launcher

The PHPUnit launcher has this bit of code that warns of an aweful hack but doesn't really explain what it's trying to do.  I'm curious why they're not just importing or requiring the .phar file?

            $alias = $phar->getAlias();
            Phar::loadPhar($path, $alias);
            //awful hack start (but I don't know a better way to do it)
            $stub = $phar->getStub();
            $i = strpos($stub, "<?php\n");
            $stub = substr($stub, $i + 6);
            $i = strpos($stub, "Phar::mapPhar");
            $stub_prefix = substr($stub, 0, $i);
            if (!isset($_SERVER['IDE_PHPUNIT_VERSION']) ||  $_SERVER['IDE_PHPUNIT_VERSION'] < "4.6") {
                eval($stub_prefix);
            }
            else {
                $mapEnd = strpos($stub, ")", $i);
                $stub_suffix = substr($stub, $mapEnd + 2);
                eval($stub_prefix . $stub_suffix);
            }
            //awful hack end