Why is this database service definition not valid?

web-excess

pipelines:
  branches:
    develop:
      - step:
          image: php:7.0
          script:
            - apt-get update && apt-get install -y unzip
            - curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer
            - composer install
          services:
            - database
definitions:
  services:
    database:
      image: mysql
      environment:
        MYSQL_DATABASE: pipelines
        MYSQL_RANDOM_ROOT_PASSWORD: yes
        MYSQL_USERNAME: pipeline_user
        MYSQL_PASSWORD: pipeline_password

web-excess

It's a bug which gets resolved:

https://bitbucket.org/site/master/issues/14471/the-pipelines-yml-file-validator-returns

https://bitbucket.org/site/master/issues/14473/pipelines-fail-when-the-environment