distillery split after

mix.exs

defmodule Systematize.Mixfile do
  use Mix.Project

  # ...
  
  defp deps do
    [
      {:phoenix, "~> 1.3.3"},
      {:phoenix_pubsub, "~> 1.0"},
      {:phoenix_html, "~> 2.10"},
      {:phoenix_live_reload, "~> 1.0", only: :dev},
      {:gettext, "~> 0.11"},
      {:cowboy, "~> 1.0"}
    ]
    |> choose_distillery
  end

  defp choose_distillery(static_deps) do
    case System.get_env("LEGACY_BUILD") do
      nil -> [{:distillery, "~> 2.0", runtime: false} | static_deps]
      _ -> [{:distillery, "~> 1.5", runtime: false} | static_deps]
    end
  end
end