src/Pure/Tools/build.scala

   Notable system settings:
 """ + Library.indent_lines(4, Build_Log.Settings.show()) + "\n",
         "A:" -> (arg => afp_root = Some(if (arg == ":") AFP.BASE else Path.explode(arg))),
         "B:" -> (arg => base_sessions += arg),
         "D:" -> (arg => select_dirs += Path.explode(arg)),
-        "H:" -> (arg => build_hosts ++= Build_Cluster.Host.parse(arg)),
+        "H:" -> (arg => build_hosts ++= Build_Cluster.Host.parse(Registry.global, arg)),
         "N" -> (_ => numa_shuffling = true),
         "P:" -> (arg => browser_info = Browser_Info.Config.make(arg)),
         "R" -> (_ => requirements = true),
         "S" -> (_ => soft_build = true),
         "X:" -> (arg => exclude_session_groups += arg),