--task-preview non-root file with subtask pointing root task

file: {root-cfg-prj}:{root-cfg-branch}:task.config

[root "Points to subFile task with rootFile task preview"]
    applicable = is:open
    pass = True
    subtask = foo/bar/baz.config^Preview pointing to rootFile task

[task "Task in rootFile"]
    applicable = is:open
    pass = True

file: {root-cfg-prj}:{root-cfg-branch}:task/foo/bar/baz.config

 [task "Preview pointing to rootFile task"]
     applicable = is:open
     pass = Fail
+    subtask = ^Task in rootFile

json:

{
   "applicable" : true,
   "hasPass" : true,
   "name" : "Points to subFile task with rootFile task preview",
   "status" : "WAITING",
   "subTasks" : [
      {
         "applicable" : true,
         "hasPass" : true,
         "name" : "Preview pointing to rootFile task",
         "status" : "READY",
         "subTasks" : [
            {
               "applicable" : true,
               "hasPass" : true,
               "name" : "Task in rootFile",
               "status" : "PASS"
            }
         ]
      }
   ]
}