# File lib/bundler/definition.rb, line 255
    def ensure_equivalent_gemfile_and_lockfile(explicit_flag = false)
      changes = false

      msg = "You are trying to install in deployment mode after changing\n" \
            "your Gemfile. Run `bundle install` elsewhere and add the\n" \
            "updated Gemfile.lock to version control."

      unless explicit_flag
        msg += "\n\nIf this is a development machine, remove the Gemfile " \
               "freeze \nby running `bundle install --no-deployment`."
      end

      added =   []
      deleted = []
      changed = []

      if @locked_sources != @sources
        new_sources = @sources - @locked_sources
        deleted_sources = @locked_sources - @sources

        if new_sources.any?
          added.concat new_sources.map { |source| "* source: #{source}" }
        end

        if deleted_sources.any?
          deleted.concat deleted_sources.map { |source| "* source: #{source}" }
        end

        changes = true
      end

      both_sources = Hash.new { |h,k| h[k] = ["no specified source", "no specified source"] }
      @dependencies.each { |d| both_sources[d.name][0] = d.source if d.source }
      @locked_deps.each  { |d| both_sources[d.name][1] = d.source if d.source }
      both_sources.delete_if { |k,v| v[0] == v[1] }

      if @dependencies != @locked_deps
        new_deps = @dependencies - @locked_deps
        deleted_deps = @locked_deps - @dependencies

        if new_deps.any?
          added.concat new_deps.map { |d| "* #{pretty_dep(d)}" }
        end

        if deleted_deps.any?
          deleted.concat deleted_deps.map { |d| "* #{pretty_dep(d)}" }
        end

        both_sources.each do |name, sources|
          changed << "* #{name} from `#{sources[0]}` to `#{sources[1]}`"
        end

        changes = true
      end

      msg << "\n\nYou have added to the Gemfile:\n"     << added.join("\n") if added.any?
      msg << "\n\nYou have deleted from the Gemfile:\n" << deleted.join("\n") if deleted.any?
      msg << "\n\nYou have changed in the Gemfile:\n"   << changed.join("\n") if changed.any?
      msg << "\n"

      raise ProductionError, msg if added.any? || deleted.any? || changed.any?
    end