QtConcurrent specifying max thread count

There should be a way to force QtConcurrent operations to serialize onto the main thread? For example, suppose I have a multi-threaded application and I'd like to provide a debug mode that serializes all threaded operations to ensure that threading is not a factor. I'd like to call an option like:

QtConcurrent::setSerializeOperations(true);

With this global parameter set, Any calls to QtConcurrent::run/map/mappedReduce/etc would be executed serially, in place,
on the calling thread.

Alternatively, this could be done by specifying:

QThreadPool::globalInstance.setMaxThreadCount(0);

This implementation would likely be even easier - as the implementation
could be:

void QThreadPool::start(QRunnable *runnable, int priority)
{
if(maxThreadCount == 0) // Serial execution

{ runnable->run(); }

else

{ // .... existing code ..... }

return;
}