rust-cpython: drop manual management of mutably_borrowed
RefCell::borrow() should guarantee there's no mutable borrow.
As a follow up, maybe PySharedState can be a pure data structure + function.
Most ref-sharing business has already been moved to PySharedRef* and PyLeaked*.
use cpython::{PyDict, PyObject, PyResult, PyTuple, Python};
#[allow(unused)]
pub fn print_python_trace(py: Python) -> PyResult<PyObject> {
eprintln!("===============================");
eprintln!("Printing Python stack from Rust");
eprintln!("===============================");
let traceback = py.import("traceback")?;
let sys = py.import("sys")?;
let kwargs = PyDict::new(py);
kwargs.set_item(py, "file", sys.get(py, "stderr")?)?;
traceback.call(py, "print_stack", PyTuple::new(py, &[]), Some(&kwargs))
}