basetemp should not be collected

when using a basetemp in the test collection source directory and adding valid, failing pytests to it the tests are collected before the basetemp directory is ensure_reset_dir'd

related to https://github.com/pytest-dev/pytest/issues/7940

def test_basetemp_not_collected(testdir):
    testdir.makepyfile(
        r"""
        def test(tmp_path):
            (tmp_path / "test_fail.py").write_text(
                "def test_fail():\n     assert False"
            )
        """
    )
    assert testdir.runpytest("--basetemp=tmp").ret == 0
    # running a second time and ensure we don't crash
    assert testdir.runpytest("--basetemp=tmp").ret == 0

Start with the supplied test_basetemp_not_collected regression test and trace how --basetemp is handled before collection. Run the test twice with the generated failing test file, and consider the issue complete when both runs return 0 without collecting that file.