Using Notify reports deadlock, while a hand-rolled event does not

[DemiMarie]

I wrote a model of a bespoke RWLock implementation with Loom. The implementation uses a bespoke semaphore primitive, which I mock using a mutex and a condition variable. This works fine. However, one of the semaphores only ever has one thread waiting on it at a time. If I use Loom’s Notify primitive to implement this, Loom reports a deadlock. This seems to be inconsistent.

To reproduce this, run the code from this Git repository twice, once with --feature notify and once without. With --feature notify Loom reports a deadlock. Otherwise, no deadlock is reported.