rust-pyo3: exposition of AncestorsIterator...
rust-pyo3: exposition of AncestorsIterator
Compared to the early experiments, we have one less `RwLock` in the
wrapping. Still that is somewhat redundant with `UnsafePyLeaked` being
itself some kind of lock.
In the original rust-cpython code, we were borrowing the `RefCell`
with a method that can panic. Instead we are now converting the
`PoisonError` that unlocking a `RwLock` can produce.
Since all methods acquiring the `RwLock` are themselves protected
by the GIL and do not release it before returning, nor do they
leak RwLock guards, there is no risk of contention on these locks
themselves.
