unable to import within test function when using fs fixture and python 2.7

[diefans]

Describe the bug

$ pipenv run pytest
========================================== test session starts ==========================================
platform linux2 -- Python 2.7.15, pytest-4.3.1, py-1.8.0, pluggy-0.9.0
rootdir: /home/olli/code/da/pyfakefs-bug, inifile:
plugins: pyfakefs-3.5.7
collected 1 item

test_foo.py F                                                                                     [100%]

=============================================== FAILURES ================================================
______________________________________________ test_import ______________________________________________

fs = <pyfakefs.fake_filesystem.FakeFilesystem object at 0x7fe551c9f310>

    def test_import(fs):
>       import foo

/home/olli/code/da/pyfakefs-bug/test_foo.py:2:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
/home/olli/code/da/pyfakefs-bug/foo.py:1: in <module>
    ???
/home/olli/.local/share/virtualenvs/pyfakefs-bug-qrOR-hXJ/lib/python2.7/site-packages/gevent/__init__.py:86: in <module>
    ???
/home/olli/.local/share/virtualenvs/pyfakefs-bug-qrOR-hXJ/lib/python2.7/site-packages/gevent/_config.py:699: in <module>
    ???
/home/olli/.local/share/virtualenvs/pyfakefs-bug-qrOR-hXJ/lib/python2.7/site-packages/gevent/_config.py:146: in get
    ???
/home/olli/.local/share/virtualenvs/pyfakefs-bug-qrOR-hXJ/lib/python2.7/site-packages/gevent/_config.py:248: in validate
    ???
/home/olli/.local/share/virtualenvs/pyfakefs-bug-qrOR-hXJ/lib/python2.7/site-packages/gevent/_config.py:219: in _import_one_of
    ???
/home/olli/.local/share/virtualenvs/pyfakefs-bug-qrOR-hXJ/lib/python2.7/site-packages/gevent/_config.py:237: in _import_one
    ???
/home/olli/.pyenv/versions/2.7.15/lib/python2.7/importlib/__init__.py:37: in import_module
    ???
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

>   ???
E   NameError: name '__import__' is not defined

src/gevent/libev/corecext.pyx:1: NameError
=========================================== warnings summary ============================================
test_foo.py::test_import
  /home/olli/.local/share/virtualenvs/pyfakefs-bug-qrOR-hXJ/lib/python2.7/site-packages/py/_code/_assertionold.py:3: DeprecationWarning: The compiler package is deprecated and removed in Python 3.x.
    from compiler import parse, ast, pycodegen

-- Docs: https://docs.pytest.org/en/latest/warnings.html
================================= 1 failed, 1 warnings in 0.19 seconds ==================================

This happens only in python 2.7.

How To Reproduce

(
DIR=$(mktemp -d)
cd ${DIR}
pipenv --python 2.7
pipenv install pytest pyfakefs gevent

cat > foo.py << EOF
import gevent
EOF

cat > test_foo.py << EOF
def test_import(fs):
    import foo
EOF

pipenv run pytest
rm -r ${DIR}
)

Your enviroment

$ pipenv run python -c "import platform; print(platform.platform())"
Linux-4.20.10-zen1-1-zen-x86_64-with-glibc2.7
$ pipenv run python -c "import sys; print('Python', sys.version)"
('Python', '2.7.15 (default, Oct  1 2018, 22:14:38) \n[GCC 5.5.0 20171010]')
$ pipenv run python -c "from pyfakefs.fake_filesystem import __version__; print('pyfakefs', __version__)"
('pyfakefs', '3.5.7')

[mrbean-bremen]

This could be a duplicate of #469. Can you please check if this also happens with current master?

[diefans]

indeed actual master fixes the issue for me.

[mrbean-bremen]

Ok, I was planning to make a new minor release anyway - I may do it later today, before this turns up again.