Can't use %paths.base% inside extensions: Failed opening required '%paths.base%'

[tomasvts]

Edit: #1455 (comment)

Hello,

This is my configuration

workspace/project/behat.yml.dist

default:
    gherkin:
        filters:
            tags: ~oauth
    calls:
        error_reporting: 16383 # E_ALL & ~E_USER_DEPRECATED
    autoload:
        '': '%paths.base%/tests/Functional/Bootstrap'
    extensions:
        FriendsOfBehat\SymfonyExtension:
            bootstrap: '%paths.base%/tests/bootstrap.php'
        rdx\behatvars\BehatVariablesExtension: ~
    suites:
        default:
            paths:
                - '%paths.base%/tests/Functional/Features'
            contexts:
                - rdx\behatvars\BehatVariablesContext
                - App\Tests\Functional\Bootstrap\SetupContext:
                - App\Tests\Functional\Bootstrap\HttpContext:

And when I execute my tests, behat does not compile the configuration, and it does not replace the placeholder %paths.base%.
I've tried with quotes, double quotes, without quotes, and all with no avail. None of them work.

The error is:

/var/www/html # behat
PHP Warning:  require_once(%paths.base%/tests/bootstrap.php): Failed to open stream: No such file or directory in /var/www/html/vendor/friends-of-behat/symfony-extension/src/ServiceContainer/SymfonyExtension.php on line 182
PHP Fatal error:  Uncaught Error: Failed opening required '%paths.base%/tests/bootstrap.php' (include_path='.:/usr/local/lib/php') in /var/www/html/vendor/friends-of-behat/symfony-extension/src/ServiceContainer/SymfonyExtension.php:182
Stack trace:
#0 /var/www/html/vendor/friends-of-behat/symfony-extension/src/ServiceContainer/SymfonyExtension.php(76): FriendsOfBehat\SymfonyExtension\ServiceContainer\SymfonyExtension->loadBootstrap()
#1 /var/www/html/vendor/behat/behat/src/Behat/Testwork/ServiceContainer/ContainerLoader.php(159): FriendsOfBehat\SymfonyExtension\ServiceContainer\SymfonyExtension->load()
#2 /var/www/html/vendor/behat/behat/src/Behat/Testwork/ServiceContainer/ContainerLoader.php(130): Behat\Testwork\ServiceContainer\ContainerLoader->loadExtension()
#3 /var/www/html/vendor/behat/behat/src/Behat/Testwork/ServiceContainer/ContainerLoader.php(67): Behat\Testwork\ServiceContainer\ContainerLoader->loadExtensions()
#4 /var/www/html/vendor/behat/behat/src/Behat/Testwork/Cli/Application.php(185): Behat\Testwork\ServiceContainer\ContainerLoader->load()
#5 /var/www/html/vendor/behat/behat/src/Behat/Testwork/Cli/Application.php(161): Behat\Testwork\Cli\Application->createContainer()
#6 /var/www/html/vendor/behat/behat/src/Behat/Testwork/Cli/Application.php(122): Behat\Testwork\Cli\Application->createCommand()
#7 /var/www/html/vendor/symfony/console/Application.php(169): Behat\Testwork\Cli\Application->doRun()
#8 /var/www/html/vendor/behat/behat/bin/behat(34): Symfony\Component\Console\Application->run()
#9 /var/www/html/vendor/bin/behat(119): include('...')
#10 {main}
  thrown in /var/www/html/vendor/friends-of-behat/symfony-extension/src/ServiceContainer/SymfonyExtension.php on line 182

I'll remove the %paths.base% placeholders for now, but I believe this is a feature that should work if the documentation says so.

[tomasvts]

Related
FriendsOfBehat/SymfonyExtension#151

[tomasvts]

Update:
The variable expansion works outside the "extensions" block.
So if I remove paths.base from the extensions block it works:

default:
    gherkin:
        filters:
            tags: ~oauth
    calls:
        error_reporting: 16383 # E_ALL & ~E_USER_DEPRECATED
    autoload:
        '': '%paths.base%/tests/Functional/Bootstrap'
    extensions:
        FriendsOfBehat\SymfonyExtension:
            bootstrap: /full/path/to/my/workspace/folder/tests/bootstrap.php
        rdx\behatvars\BehatVariablesExtension: ~
    suites:
        default:
            paths:
                - '%paths.base%/tests/Functional/Features'
            contexts:
                - rdx\behatvars\BehatVariablesContext
                - App\Tests\Functional\Bootstrap\SetupContext:
                - App\Tests\Functional\Bootstrap\HttpContext: