Cython debugger cygdb: Error occurred in Python: 'PyDictObjectPtr' object has no attribute 'items'

I have the following three files:

$ cat fib.pyx
#cython: language_level=3
def fibonacci(n):
    cdef int a, b, i
    a, b = 1, 1
    for i in range(1, n):
        a, b = b, a+b
    return b

$ cat t.py
from fib import fibonacci

print(fibonacci(10))

$ cat setup.py
from setuptools import setup
from Cython.Build import cythonize

from setuptools import Extension, setup

extensions = [
    Extension(
        "fib",
        ["fib.pyx"],
        extra_compile_args=["-g"],
    )
]

setup(
    name="source",
    ext_modules=cythonize(
        extensions, gdb_debug=True
    ),
)

I then run

python setup.py build_ext --inplace  -f --debug
cygdb

Then, inside cygdb:

warning: .cygdbinit: No such file or directory
(gdb) cy break fibonacci
Function "__pyx_pw_3fib_1fibonacci" not defined.
Breakpoint 1 (__pyx_pw_3fib_1fibonacci) pending.
(gdb) cy run t.py
Warning: 'set logging on', an alias for the command 'set logging enabled', is deprecated.
Use 'set logging enabled on'.


Breakpoint 1, __pyx_pw_3fib_1fibonacci (__pyx_self=0x0, __pyx_v_n=10) at fib.c:1218
1218    static PyObject *__pyx_pw_3fib_1fibonacci(PyObject *__pyx_self, PyObject *__pyx_v_n) {
2    def fibonacci(n):
(gdb) cy print locals
Python Exception <class 'AttributeError'>: 'PyDictObjectPtr' object has no attribute 'items'
Error occurred in Python: 'PyDictObjectPtr' object has no attribute 'items'

What does this error mean? I was expecting it to print out the value of n. Am I running it correctly? Have I passed the right arguments to cythonize?

I'm running Ubuntu 22.04.1 via WSL2

Python 3.8.14

Cython 0.29.32

gdb 12.0.90

I've also done sudo apt install python3.8-dbg