Hello, I am getting an "already borrowed" error when using nested rayon threads and a RefCell object. I have a repro here

What I don't understand is why the creation of a new independent thread pool, with threads that don't access the RefCell in any way, they just do a println, are causing an extra borrow to even be attempted? Is this a bug or am I missing something when creating this thread pool?

n.b. If I just use a regular thread, instead of a rayon thread, everything works as expected as seen here