Exception trace:
() at /home/rud5g/magento-ce/vendor/magento-hackathon/magento-composer-installer/src/MagentoHackathon/Composer/Magento/Installer.php:506
Composer\Util\ErrorHandler::handle() at n/a:n/a
mkdir() at /home/rud5g/magento-ce/vendor/magento-hackathon/magento-composer-installer/src/MagentoHackathon/Composer/Magento/Installer.php:506
MagentoHackathon\Composer\Magento\Installer->setMagentoPermissions() at /home/rud5g/magento-ce/vendor/magento-hackathon/magento-composer-installer/src/MagentoHackathon/Composer/Magento/Installer.php:496
MagentoHackathon\Composer\Magento\Installer->prepareMagentoCore() at /home/rud5g/magento-ce/vendor/magento-hackathon/magento-composer-installer/src/MagentoHackathon/Composer/Magento/Installer.php:471
MagentoHackathon\Composer\Magento\Installer->appendGitIgnore() at /home/rud5g/magento-ce/vendor/magento-hackathon/magento-composer-installer/src/MagentoHackathon/Composer/Magento/Installer.php:415
MagentoHackathon\Composer\Magento\Installer->install() at phar:///home/rud5g/magento-ce/composer.phar/src/Composer/Installer/InstallationManager.php:153
Composer\Installer\InstallationManager->install() at phar:///home/rud5g/magento-ce/composer.phar/src/Composer/Installer/InstallationManager.php:140
Composer\Installer\InstallationManager->execute() at phar:///home/rud5g/magento-ce/composer.phar/src/Composer/Installer.php:540
Composer\Installer->doInstall() at phar:///home/rud5g/magento-ce/composer.phar/src/Composer/Installer.php:214
Composer\Installer->run() at phar:///home/rud5g/magento-ce/composer.phar/src/Composer/Command/InstallCommand.php:123
Composer\Command\InstallCommand->execute() at phar:///home/rud5g/magento-ce/composer.phar/vendor/symfony/console/Symfony/Component/Console/Command/Command.php:241
Symfony\Component\Console\Command\Command->run() at phar:///home/rud5g/magento-ce/composer.phar/vendor/symfony/console/Symfony/Component/Console/Application.php:892
Symfony\Component\Console\Application->doRunCommand() at phar:///home/rud5g/magento-ce/composer.phar/vendor/symfony/console/Symfony/Component/Console/Application.php:191
Symfony\Component\Console\Application->doRun() at phar:///home/rud5g/magento-ce/composer.phar/src/Composer/Console/Application.php:117
Composer\Console\Application->doRun() at phar:///home/rud5g/magento-ce/composer.phar/vendor/symfony/console/Symfony/Component/Console/Application.php:121
Symfony\Component\Console\Application->run() at phar:///home/rud5g/magento-ce/composer.phar/src/Composer/Console/Application.php:83
Composer\Console\Application->run() at phar:///home/rud5g/magento-ce/composer.phar/bin/composer:43
require() at /home/rud5g/magento-ce/composer.phar:15
install [--prefer-source] [--prefer-dist] [--dry-run] [--dev] [--no-dev] [--no-plugins] [--no-custom-installers] [--no-scripts] [--no-progress] [-v|vv|vvv|--verbose] [-o|--optimize-autoloader] [packages1] ... [packagesN]
apparently, by setting auto-append-gitignore, the function setMagentoPermissions is called before extracting core/magento, so mkdir is called without recursive or parent directories.
composer.json file