src/Pure/Build/build_schedule.scala

     session_setup: (String, Session) => Unit = (_, _) => (),
     cache: Term.Cache = Term.Cache.make()
   ): Schedule = {
     val build_engine = new Engine
 
-    val store = build_engine.build_store(options, build_hosts = build_hosts, cache = cache)
+    val store =
+      build_engine.build_store(options, build_cluster = build_hosts.nonEmpty, cache = cache)
     val log_store = Build_Log.store(options, cache = cache)
     val build_options = store.options
 
     def build_schedule(
       server: SSH.Server,