Usando composer customizado no tsuru

tsuru.yml

php:
    version: 5.6
    composer: false
    frontend:
        name: apache
        options:
            modules:
                - rewrite
    interpretor:
        name: fpm55
        options:
            extensions:
                - php-mysql
                - php-xml
                - php-mbstring
                - php-zip
hooks:
  build:
    - sudo apt-get install wget xz-utils -y
    - php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
    - php -r "if (hash_file('SHA384', 'composer-setup.php') === '669656bab3166a7aff8a7506b8cb2d1c292f042046c5a994c43155c0be6190fa0355160742ab2e1c88d40d5be660b410') { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;"
    - php composer-setup.php
    - php -r "unlink('composer-setup.php');"
    - php composer.phar global require fxp/composer-asset-plugin --no-plugins
    - php composer.phar update --prefer-dist -vvv --profile