Scripts using the XdebugHandler componant will load PHP extensions twice on a Nix environment

xdebug-handler-nix-boom.php

<?php

require __DIR__ . '/vendor/autoload.php';

// Most PHP CLI tools run this snippet to disable Xdebug at runtime
use Composer\XdebugHandler\XdebugHandler;

$xdebug = new XdebugHandler('myCliApp');
$xdebug->setPersistent();
$xdebug->check();
unset($xdebug);

// This will contains the ini script created by XdebugHandler without the xdebug extension
echo 'PHPRC: ', getenv('PHPRC'), PHP_EOL;

// This should be empty, but on a Nix environment, the PHP binary is wrapped in a bash script
// which export PHP_INI_SCAN_DIR with a fixed value and then run the actual PHP binary with the exec command.
// Consequently, PHP extensions are loaded twice.
echo 'PHP Scan Dir : ', getenv('PHP_INI_SCAN_DIR'), PHP_EOL;

To quickly reproduce the issue:

With XDebug extension

1. Create a simple composer.json containing a require section as such:

...8<...
    "require": {
        "ext-xdebug": "*"
    },
...>8...

2. Launch:

nix shell github:loophp/nix-shell#env-php81 --impure

3. Run composer install:

composer install

4. Download the test script from this gist:

wget https://gist.githubusercontent.com/guillemcanal/92f4a97bb31d25522a9a7658a5ff5019/raw/563e406374eed3d2994f9118d6ed381ab1ac721c/xdebug-handler-nix-boom.php

5. php xdebug-handler-nix-boom.php

Without XDebug extension

1. Launch:

nix shell github:loophp/nix-shell#env-php81

3. Run composer install:

composer install

4. Download the test script from this gist:

wget https://gist.githubusercontent.com/guillemcanal/92f4a97bb31d25522a9a7658a5ff5019/raw/563e406374eed3d2994f9118d6ed381ab1ac721c/xdebug-handler-nix-boom.php

5. php xdebug-handler-nix-boom.php