FWIW, I don't support adding this functionality.  I don't see precedents for Condition Variables behaving this way in other languages.  Also, I don't think it is worth the added complexity, learning curve, and maintenance burden.  Condition variables are used as primitive for other mutexes and I think we ought to keep them somewhat simple.

If someone wants to notify a specific waiter, then they have other options  such as using a separate condition variable that shares the same underlying lock (much as the code in the queue module does).  That approach is easy to reason about.