Argument --env dont work with advanced assignments

[manuelcanepa]

Many pipelines need a custom auth.json that will be passed as env to be secure. Ie:

        name: Initial Setup
        caches:
          - composer
        script:
          - echo "$AUTH" > auth.json
          - php -d memory_limit=-1 $(which composer) install --prefer-dist
        artifacts:
          - vendor/**

The parseVars function is very simple and need to be more complex for this scenarios.