src/Pure/Admin/build_doc.scala

     system_mode: Boolean = false,
     docs: List[String] = Nil): Int =
   {
     val selection =
       for {
-        (name, info) <- Sessions.load(options).build_topological_order
+        info <- Sessions.load(options).build_topological_order
         if info.groups.contains("doc")
         doc = info.options.string("document_variants")
         if all_docs || docs.contains(doc)
-      } yield (doc, name)
+      } yield (doc, info.name)
 
     val selected_docs = selection.map(_._1)
     val sessions = selection.map(_._2)
 
     docs.filter(doc => !selected_docs.contains(doc)) match {