class Bundler::Definition

def ensure_equivalent_gemfile_and_lockfile(explicit_flag = 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 = []
  gemfile_sources = sources.lock_sources
  if @locked_sources != gemfile_sources
    new_sources = gemfile_sources - @locked_sources
    deleted_sources = @locked_sources - gemfile_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
  end
  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 = Hash.new { |h,k| h[k] = [] }
  @dependencies.each { |d| both_sources[d.name][0] = d }
  @locked_deps.each  { |d| both_sources[d.name][1] = d.source }
  both_sources.each do |name, (dep, lock_source)|
    if (dep.nil? && !lock_source.nil?) || (!dep.nil? && !lock_source.nil? && !lock_source.can_lock?(dep))
      gemfile_source_name = (dep && dep.source) || 'no specified source'
      lockfile_source_name = lock_source || 'no specified source'
      changed << "* #{name} from `#{gemfile_source_name}` to `#{lockfile_source_name}`"
    end
  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