class Bundler::Definition

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