test_textbox3 failing with v1.24.2

[Antiz96]

Description of the bug

Hello,

The test_textbox3 (in test_textbox.py) is failing with v1.24.2 (but passes fine with v1.24.1):

==================================== ERRORS ====================================
______________________ ERROR at teardown of test_textbox3 ______________________

args = (), kwargs = {}, wt = 'format error: Reserved charstring byte'
@py_assert1 = False
@py_format2 = "Warnings text not empty: wt='format error: Reserved charstring byte'\n>assert not 'format error: Reserved charstring byte'"
rep = None

    @pytest.fixture(autouse=True)
    def wrap(*args, **kwargs):
        '''
        Check that tests return with empty MuPDF warnings buffer. For example this
        detects failure to call fz_close_output() before fz_drop_output(), which
        (as of 2024-4-12) generates a warning from MuPDF.
        '''
        wt = fitz.TOOLS.mupdf_warnings()
        assert not wt, f'{wt=}'

        # Run the test.
        rep = yield

        # Test has run; check it did not create any MuPDF warnings.
        wt = fitz.TOOLS.mupdf_warnings()
        if not hasattr(fitz, 'mupdf'):
            print(f'Not checking mupdf_warnings on classic.')
        else:
>           assert not wt, f'Warnings text not empty: {wt=}'
E           AssertionError: Warnings text not empty: wt='format error: Reserved charstring byte'
E           assert not 'format error: Reserved charstring byte'

tests/conftest.py:22: AssertionError
----------------------------- Captured stderr call -----------------------------
MuPDF error: format error: Reserved charstring byte
=========================== short test summary info ============================
ERROR tests/test_textbox.py::test_textbox3 - AssertionError: Warnings text no...

cc @dvzrv

How to reproduce the bug

• Compile pymupdf v1.24.2
• Run tests and see the above one failing

(Tested on both Python 3.11 and 3.12 FWIW)

PyMuPDF version

1.24.2

Operating system

Linux

Python version

3.11