# File lib/librarian/action/update.rb, line 12
      def run
        unless lockfile_path.exist?
          raise Error, "Lockfile missing!"
        end
        previous_resolution = lockfile.load(lockfile_path.read)
        spec = specfile.read(previous_resolution.sources)
        changes = spec_change_set(spec, previous_resolution)
        manifests = changes.same? ? previous_resolution.manifests : changes.analyze
        partial_manifests = ManifestSet.deep_strip(manifests, dependency_names)
        unpinnable_sources = previous_resolution.sources - partial_manifests.map(&:source)
        unpinnable_sources.each(&:unpin!)

        resolution = resolver.resolve(spec, partial_manifests)
        persist_resolution(resolution)
      end