PyO3 is incompatible with `ctypes`

For a personal project, I'm trying to provide a Rust callback function to a Python module as a raw function pointer. However, if I attempt to acquire the GIL within the callback function, it causes the program to panic due to out-of-order GIL dropping. As a minimal example:

use pyo3::prelude::*;

extern "C" fn callback() {
    println!("begin callback");
    let _ = Python::acquire_gil();
    println!("end callback");
}

fn main() -> PyResult<()> {
    Python::with_gil(|py| {
        PyModule::import(py, "ctypes")?
            .call_method1("CFUNCTYPE", ((),))?
            .call1((callback as *const () as usize,))?
            .call0()?;
        Ok(())
    })
}

The program panics before end callback can be printed:

$ target/debug/gil_test 
begin callback
thread 'main' panicked at 'The first GILGuard acquired must be the last one dropped.', /home/lm978/.cargo/registry/src/github.com-1ecc6299db9ec823/pyo3-0.13.2/src/gil.rs:290:17
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
thread 'main' panicked at 'The first GILGuard acquired must be the last one dropped.', /home/lm978/.cargo/registry/src/github.com-1ecc6299db9ec823/pyo3-0.13.2/src/gil.rs:290:17
stack backtrace:
   0:     0x5599ade9a3b0 - std::backtrace_rs::backtrace::libunwind::trace::h04d12fdcddff82aa
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/../../backtrace/src/backtrace/libunwind.rs:100:5
   1:     0x5599ade9a3b0 - std::backtrace_rs::backtrace::trace_unsynchronized::h1459b974b6fbe5e1
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x5599ade9a3b0 - std::sys_common::backtrace::_print_fmt::h9b8396a669123d95
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/sys_common/backtrace.rs:67:5
   3:     0x5599ade9a3b0 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::he009dcaaa75eed60
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/sys_common/backtrace.rs:46:22
   4:     0x5599adeb383c - core::fmt::write::h77b4746b0dea1dd3
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/core/src/fmt/mod.rs:1078:17
   5:     0x5599ade98252 - std::io::Write::write_fmt::heb7e50902e98831c
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/io/mod.rs:1518:15
   6:     0x5599ade9c515 - std::sys_common::backtrace::_print::h2d880c9e69a21be9
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/sys_common/backtrace.rs:49:5
   7:     0x5599ade9c515 - std::sys_common::backtrace::print::h5f02b1bb49f36879
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/sys_common/backtrace.rs:36:9
   8:     0x5599ade9c515 - std::panicking::default_hook::{{closure}}::h658e288a7a809b29
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/panicking.rs:208:50
   9:     0x5599ade9c1b8 - std::panicking::default_hook::hb52d73f0da9a4bb8
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/panicking.rs:227:9
  10:     0x5599ade9cc51 - std::panicking::rust_panic_with_hook::hfe7e1c684e3e6462
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/panicking.rs:593:17
  11:     0x5599ade81d4e - std::panicking::begin_panic::{{closure}}::h67f425c0631152f9
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/panicking.rs:522:9
  12:     0x5599ade81bd9 - std::sys_common::backtrace::__rust_end_short_backtrace::h726b4232d880f43b
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/sys_common/backtrace.rs:141:18
  13:     0x5599ade81c7b - std::panicking::begin_panic::h4b52fd2d813c0948
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/panicking.rs:521:12
  14:     0x5599ade60896 - <pyo3::gil::GILGuard as core::ops::drop::Drop>::drop::{{closure}}::h8e6c3302036811a8
                               at /home/lm978/.cargo/registry/src/github.com-1ecc6299db9ec823/pyo3-0.13.2/src/gil.rs:290:17
  15:     0x5599ade62dc1 - std::thread::local::LocalKey<T>::try_with::hd7fb52379d7bc09d
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/thread/local.rs:272:16
  16:     0x5599ade60798 - <pyo3::gil::GILGuard as core::ops::drop::Drop>::drop::h5070dea984a3f707
                               at /home/lm978/.cargo/registry/src/github.com-1ecc6299db9ec823/pyo3-0.13.2/src/gil.rs:285:17
  17:     0x5599ade6c57f - core::ptr::drop_in_place::hca1b1d785a584a01
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/core/src/ptr/mod.rs:175:1
  18:     0x5599ade6c2c0 - core::ptr::drop_in_place::h7d2dc00e35e21d91
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/core/src/ptr/mod.rs:175:1
  19:     0x5599ade6c5ff - core::ptr::drop_in_place::hddef70a15a5993ae
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/core/src/ptr/mod.rs:175:1
  20:     0x5599ade5e144 - pyo3::python::Python::with_gil::ha183e49a7426795a
                               at /home/lm978/.cargo/registry/src/github.com-1ecc6299db9ec823/pyo3-0.13.2/src/python.rs:158:5
  21:     0x5599ade5dc91 - pyo3_test::main::h0624e64f2681f1e6
                               at /home/lm978/nested/pyo3_test/src/main.rs:10:5
  22:     0x5599ade5e642 - core::ops::function::FnOnce::call_once::h7c181d0d3d6c9cdf
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/core/src/ops/function.rs:227:5
  23:     0x5599ade5dbaa - std::sys_common::backtrace::__rust_begin_short_backtrace::haa621927d913d7d2
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/sys_common/backtrace.rs:125:18
  24:     0x5599ade5deb6 - std::rt::lang_start::{{closure}}::he8806ad14534304d
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/rt.rs:66:18
  25:     0x5599ade9d167 - core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &F>::call_once::h57e2a071d427b24c
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/core/src/ops/function.rs:259:13
  26:     0x5599ade9d167 - std::panicking::try::do_call::h81cbbe0c3b30a28e
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/panicking.rs:381:40
  27:     0x5599ade9d167 - std::panicking::try::hbeeb95b4e1f0a876
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/panicking.rs:345:19
  28:     0x5599ade9d167 - std::panic::catch_unwind::h59c48ccb40a0bf20
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/panic.rs:396:14
  29:     0x5599ade9d167 - std::rt::lang_start_internal::ha53ab63f88fee728
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/rt.rs:51:25
  30:     0x5599ade5de87 - std::rt::lang_start::h1e6a375f16e4e70e
                               at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/rt.rs:65:5
  31:     0x5599ade5dcca - main
  32:     0x7f930dcc2bf7 - __libc_start_main
  33:     0x5599ade5d4ca - _start
  34:                0x0 - <unknown>
thread panicked while panicking. aborting.
Illegal instruction (core dumped)

However, it can clearly be seen that the GILGuards are dropped in the correct order. Is this panic caused by a bug in PyO3, or am I doing something incorrectly?

The report points to pyo3-0.13.2/src/gil.rs and src/python.rs, with a reproducer in the shown main.rs. Start by running the minimal ctypes callback example and tracing GILGuard acquisition and drop order. Done means determining whether the panic is a PyO3 bug or misuse, then fixing the behavior or documenting the required usage with a regression test.