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.

--- a/rust/hg-pyo3/src/lib.rs	Sat Dec 07 18:24:24 2024 +0100
+++ b/rust/hg-pyo3/src/lib.rs	Sat Dec 07 18:38:37 2024 +0100
@@ -1,5 +1,6 @@
 use pyo3::prelude::*;
 
+mod ancestors;
 mod convert_cpython;
 mod dagops;
 mod exceptions;
@@ -17,6 +18,7 @@
     let name: String = m.getattr("__name__")?.extract()?;
     let dotted_name = format!("mercurial.{}", name);
 
+    m.add_submodule(&ancestors::init_module(py, &dotted_name)?)?;
     m.add_submodule(&dagops::init_module(py, &dotted_name)?)?;
     m.add("GraphError", py.get_type::<exceptions::GraphError>())?;
     Ok(())