Deadlock in QDBusConnectionPrivate

I am running across an intermittent deadlock in initialization of my Qt program, while it's relatively idle and in the event loop.

I confirmed this was a futex_wait by using strace, and I always see an entry like this for the main thread:
[pid  1812] futex(0x7f28f400aecc, FUTEX_WAIT_PRIVATE, 1, NULL <unfinished ...>

I found out that I could add a Qt event filter, and therefore log events as they are processed from the main thread. Here's a snippet for that:

    bool ActivityEventFilter::eventFilter(QObject *obj, QEvent *ev){
    VLOG(5) << "inspecting event " << obj << " name " << obj->objectName().toStdString() << " class " << obj->metaObject()->className() << " eventType " << ev->type();

      if (VLOG_IS_ON(5))
      {
        if (ev->type() == QEvent::MetaCall)
        {
            if (QString(obj->metaObject()->className()).contains("QDBusConnectionPrivate")
            {
                VLOG(5) << "Dumping object data";
                obj->dumpObjectInfo();
                obj->dumpObjectTree();
            }
        }
      }
      ...
    }

And examining my logging, the freeze always is preceded by these lines:
     

    I0614 17:18:27.928889  1812 ActivityEventFilter.cpp:19] inspecting event 0x7fde200144c0 name  class QDBusConnectionPrivate eventType 43
    I0614 17:18:27.928901 1812 ActivityEventFilter.cpp:28] Dumping object data

 
There is no output from the object info or from the object tree. I am flushing the logs

I am not consciously using DBus anywhere in my application, so I'm looking to find a way to track down who is calling it to see if it can be prevented, but without the objectInfo, I don't know where to start.

I found two Qt bug reports:
https://bugreports.qt.io/browse/QTBUG-42189

https://bugreports.qt.io/browse/QTBUG-51648

The first looks like the same type of problem, but it appears all the resolutions went into Qt 5.4.0. (I'm using Qt 5.4.1)
The second looks like a bit different behavior to me.