py38: do not call None() directly
py38: do not call None() directly

Works around:

    _____ ERROR collecting testing/io/test_saferepr.py _____
    src/_pytest/python.py:502: in _importtestmodule
        mod = self.fspath.pyimport(ensuresyspath=importmode)
    .venv38/lib/python3.8/site-packages/py/_path/local.py:701: in pyimport
        __import__(modname)
    <frozen importlib._bootstrap>:991: in _find_and_load
        ???
    <frozen importlib._bootstrap>:975: in _find_and_load_unlocked
        ???
    <frozen importlib._bootstrap>:671: in _load_unlocked
        ???
    src/_pytest/assertion/rewrite.py:136: in exec_module
        source_stat, co = _rewrite_test(fn, self.config)
    src/_pytest/assertion/rewrite.py:288: in _rewrite_test
        co = compile(tree, fn, "exec", dont_inherit=True)
    E     File "…/Vcs/pytest/testing/io/test_saferepr.py", line 45
    E       None()
    E       ^
    E   SyntaxError: 'NoneType' object is not callable; perhaps you missed a comma?

The-Compiler/pytest,nicoddemus/pytest,nicoddemus/pytest,pytest-dev/pytest,markshao/pytest,alfredodeza/pytest,RonnyPfannschmidt/pytest,Akasurde/pytest,The-Compiler/pytest