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Installing dependencies from lock file
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Installation request for symfony/browser-kit == 9999999-dev -> satisfiable by symfony/browser-kit dev-master.
    - Can only install one of: symfony/yaml dev-master, symfony/yaml 2.1.x-dev.
    - don't install symfony/symfony 2.1.x-dev|don't install symfony/browser-kit dev-master
    - don't install symfony/symfony dev-master|don't install symfony/browser-kit dev-master
    - don't install symfony/symfony 2.2.x-dev|don't install symfony/browser-kit dev-master
    - Installation request for symfony/yaml == 9999999-dev -> satisfiable by symfony/yaml dev-master.
    - Installation request for symfony/yaml == 2.1.9999999.9999999-dev -> satisfiable by symfony/symfony 2.1.x-dev, symfony/symfony dev-master, symfony/symfony 2.2.x-dev, symfony/yaml 2.1.x-dev.