Description:
------------
https://phpbugs-embeddedserver-ttohstztwy.now.sh/_src/?f=Dockerfile

If I provide a ./router.php file & a docroot ./public

The server works as expected until I receiving a fatal error in a php script (e.g. ./public/kill.php). 

Then the server is stuck to the following error for all PHP scripts : 

Warning: Unknown: failed to open stream: No such file or directory in Unknown on line 0
Fatal error: Unknown: Failed opening required 'router.php' (include_path='.:') in Unknown on line 0

Note the bug is produced only if the router.php file provide a "return false;" statement on PHP script. If I handle php script via include (e.g. ./router-fix.php), everything works as expected.

Test script:
---------------
<?php
/** 
 * 
 * Run with RELATIVE paths
 * 
 * $ php -S 127.0.0.1:8089 -t ./public router.php
 * 
 * then go to /script-that-produce-a-fatal.php
 * 
 * Next hit on php script will produce strange error.
 */

$uri = urldecode(
    parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH)
);


if ($uri !== '/' && file_exists(__DIR__.'/public/'.$uri)) {
    return false;
} else {
    return readfile(__DIR__ . '/public/index.html');
}

Expected result:
----------------
Then the server is stuck to the following error for all PHP scripts : 

Warning: Unknown: failed to open stream: No such file or directory in Unknown on line 0
Fatal error: Unknown: Failed opening required 'router.php' (include_path='.:') in Unknown on line 0