Patched os.open does not respect O_NOFOLLOW

[vector-of-bool]

Describe the bug
POSIX open() supports an O_NOFOLLOW flag. If the file being opened is a symlink, open should fail with ELOOP. pyfakefs unconditionally follows symbolic links for open.

How To Reproduce

def open_nofollow(s: Path):
    s.unlink(missing_ok=True)
    s.symlink_to("nowhere")
    with pytest.raises(OSError) as exc:
        os.open(s, os.O_RDONLY | os.O_NOFOLLOW)
    assert exc.value.errno == errno.ELOOP

def test_realfs():
    open_nofollow(Path("file.txt"))

def test_fakefs(fs):
    open_nofollow(Path("file.txt"))

Your environment
Please run the following in the environment where the problem happened and
paste the output.

$ python -c "import platform; print(platform.platform())"
Linux-6.7.6-arch1-1-x86_64-with-glibc2.39
$ python -c "import sys; print('Python', sys.version)"
Python 3.11.7 (main, Jan 29 2024, 16:03:57) [GCC 13.2.1 20230801]
$ python -c "from pyfakefs import __version__; print('pyfakefs', __version__)"
pyfakefs 5.4.dev0
$ python -c "import pytest; print('pytest', pytest.__version__)"
pytest 7.2.0

---

Thanks for the quick turnaround on all these issues! My own project very heavily tests and uses low-level filesystem functionality that is less commonly seen, hence the barrage of issues.

[mrbean-bremen]

That's ok, I appreciate that! It may take a bit until they all get resolved (my free time varies, and it takes longer for some issues), but this helps a lot.
A few years ago, we had somebody who used his own testing language to test pyfakefs, and he found a lot of mostly low-level issues (these are flagged with TSTL - there are 136 of them). This was very helpful too (though took also quite a bit of time to fix), and you are still far from that mark 😁