title: Pipeline in bitbucket failed by composer error
body: <p>I try pipeline in bitbucket. This is default conf which I am using:</p>
  
  <pre><code># This is a sample build configuration for PHP.
  # Check our guides at https://confluence.atlassian.com/x/e8YWN for more examples.
  # Only use spaces to indent your .yml configuration.
  # -----
  # You can specify a custom docker image from Docker Hub as your build environment.
  image: php:5.6.36
  pipelines:
    default:
      - step:
        caches:
          - composer
        script:
          - apt-get update &amp;&amp; apt-get install -y unzip
          - curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer
          - composer install
          - vendor/bin/phpunit
  </code></pre>
  
  <p>I am getting this error</p>
  
  <pre><code>+ composer install
    Do not run Composer as root/super user! See https://getcomposer.org/rootfor details
    Composer could not find a composer.json file in /opt/atlassian/pipelines/agent/build
    To initialize a project, please create a composer.json file as described in the https://getcomposer.org/ "Getting Started" section
  </code></pre>
  
  <p>Even when I created composer.json (all path as well) in /opt/atlassian/pipelines/agent/build.</p>
  
  <p>Btw, why tool looking for composer in such path? I have installed composer on /home/username/.composer</p>
  
  <p>What did I do wrong?</p>