Random test failure in charpoly_frobenius

[tobiasdiez]

Steps To Reproduce

No response

Expected Behavior

Tests pass

Actual Behavior

File "src/sage/schemes/cyclic_covers/charpoly_frobenius.py", line 146, in sage.schemes.cyclic_covers.charpoly_frobenius.charpoly_frobenius
Failed example:
    charpoly_frobenius(M,
    [31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16,
     15, 14, 13, 12] + [11]*21, 1129, 1, 1)
Exception raised:
    Traceback (most recent call last):
      File "/home/runner/work/sage/sage/src/sage/doctest/forker.py", line 712, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/runner/work/sage/sage/src/sage/doctest/forker.py", line 1147, in compile_and_execute
        exec(compiled, globs)
      File "<doctest sage.schemes.cyclic_covers.charpoly_frobenius.charpoly_frobenius[17]>", line 1, in <module>
        charpoly_frobenius(M,
      File "/home/runner/work/sage/sage/src/sage/schemes/cyclic_covers/charpoly_frobenius.py", line 206, in charpoly_frobenius
        assert cp[-1] == 1
    AssertionError

Additional Information

Only seen once so far at https://github.com/sagemath/sage/actions/runs/7465929817/job/20316182845?pr=37038

Environment

Conda? Linux?

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

[mkoeppe]

debian-bullseye-standard
https://github.com/sagemath/sage/actions/runs/7852863047/job/21431835641?pr=37277#step:11:11898