Sean Gallardy provides an explanation:
Sparked by my friends at Straight Path SQL, we’re going to look at a rare cause of non-yielding scheduler dumps. This is another one of those items that I meant to write about a long time ago when I worked in Support and then, well, I suck and clearly forgot about it. This should give you an idea of how rare this specific issue hits.
Read on to see what might cause this scenario and why you’re likely never to see it in the wild.
Though now that I’ve typed it, I’m sure someone will take that as a challenge.