CI failure: `SystemError: calling remove_from_pari_stack() inside sig_on()` in `binomial` in `matrix2.pyx:20953`

[user202729]

Steps To Reproduce

https://github.com/sagemath/sage/actions/runs/18240400963

[Failed example:: src/sage/matrix/matrix2.pyx#L20953](https://github.com/sagemath/sage/pull/40976/files#annotation_39819808104)
Failed example:: Exception raised:
Traceback (most recent call last):
  File "/home/runner/work/sage/sage/src/sage/doctest/forker.py", line 733, in _run
    self.compile_and_execute(example, compiler, test.globs)
  File "/home/runner/work/sage/sage/src/sage/doctest/forker.py", line 1157, in compile_and_execute
    exec(compiled, globs)
  File "<doctest sage.matrix.matrix2._matrix_power_symbolic[2]>", line 1, in <module>
    B = A**n; B
        ~^^~
  File "sage/matrix/matrix0.pyx", line 6151, in sage.matrix.matrix0.Matrix.__pow__
  File "sage/matrix/matrix2.pyx", line 21103, in sage.matrix.matrix2._matrix_power_symbolic
  File "sage/symbolic/function.pyx", line 1054, in sage.symbolic.function.BuiltinFunction.__call__
  File "sage/symbolic/expression.pyx", line 9703, in sage.symbolic.expression.Expression.binomial
SystemError: calling remove_from_pari_stack() inside sig_on()

Expected Behavior

Actual Behavior

Additional Information

No response

Environment

• OS: CI, Conda (ubuntu, Python 3.12, all, editable)
• Sage Version: 560516c

Checklist

• I have searched the existing issues for a bug report that matches the one I want to file, without success.
• I have read the documentation and troubleshoot guide

[user202729]

I suspect the reason is that some Python API gets called which might trigger the garbage collector.

One Python API is the try/finally, which there doesn't seem to be a convenient way around it: cython/cython#7189 . Another Python API being called is the conversion from Python arbitrary object to bint (after all, __nonzero__ may call arbitrary Python code), which I try to eliminate in https://github.com/sagemath/sage/compare/develop...user202729:sage:expression-convert-to-bint?expand=1 .