is_readable() not working on files inside phar

Description

Using the following code to create a basic phar file:

$stub = <<<STUB
<?php
    Phar::interceptFileFuncs();
    set_include_path('phar://' . __FILE__ . PATH_SEPARATOR . get_include_path());
    include "index.php";   
    
    __HALT_COMPILER();
STUB;

$index = <<<INDEX
<?php
    var_dump(file_exists('phar:///path/to/archive.phar/index.php')) . PHP_EOL;
    var_dump(is_readable('phar:///path/to/archive.phar/index.php')) . PHP_EOL;
    var_dump(file_exists('index.php')) . PHP_EOL;
    var_dump(is_readable('index.php')) . PHP_EOL;
INDEX;

$phar = new Phar('archive.phar');
$phar->addFromString('index.php', $index);
$phar->setStub($stub);

Then executing the following code:

php archive.phar

Resulted in this output:

bool(true)
bool(false)
bool(true)
bool(false)

But I expected this output instead:

bool(true)
bool(true)
bool(true)
bool(true)

Or executing the following code:

<?php
var_dump(is_readable('phar:///path/to/archive.phar/index.php'));

Resulted in this output:

bool(false)

But I expected this output instead:

bool(true)

PHP Version

PHP 8.0.12

Operating System

Ubuntu 20.04

Reproduce the behavior using the supplied archive.phar, index.php, and Phar stub on PHP 8.0.12. Start by tracing Phar::interceptFileFuncs() and the is_readable() path, then add or update a regression test showing that files inside the Phar report the expected readable status.