[WIP] Don't use development version of Python 3.8 in travis

[Alexander-N]

No description provided.

[Alexander-N]

CI fails for Python 3.8. I'm clueless why, any hints would be appreciated.

Traceback (most recent call last):
  File "/home/travis/virtualenv/python3.8.0/lib/python3.8/site-packages/tox/helper/build_isolated.py", line 11, in <module>
    basename = backend.build_sdist(dist_folder, {"--global-option": ["--formats=gztar"]})
  File "/home/travis/build/PyO3/pyo3/examples/rustapi_module/.tox/.package/lib/python3.8/site-packages/setuptools/build_meta.py", line 212, in build_sdist
    return self._build_with_temp_dir(['sdist', '--formats', 'gztar'],
  File "/home/travis/build/PyO3/pyo3/examples/rustapi_module/.tox/.package/lib/python3.8/site-packages/setuptools/build_meta.py", line 194, in _build_with_temp_dir
    self.run_setup()
  File "/home/travis/build/PyO3/pyo3/examples/rustapi_module/.tox/.package/lib/python3.8/site-packages/setuptools/build_meta.py", line 142, in run_setup
    exec(compile(code, __file__, 'exec'), locals())
  File "setup.py", line 82, in <module>
    setup(
  File "/home/travis/build/PyO3/pyo3/examples/rustapi_module/.tox/.package/lib/python3.8/site-packages/setuptools/__init__.py", line 145, in setup
    return distutils.core.setup(**attrs)
  File "/opt/python/3.8.0/lib/python3.8/distutils/core.py", line 148, in setup
    dist.run_commands()
  File "/opt/python/3.8.0/lib/python3.8/distutils/dist.py", line 966, in run_commands
    self.run_command(cmd)
  File "/opt/python/3.8.0/lib/python3.8/distutils/dist.py", line 985, in run_command
    cmd_obj.run()
  File "/home/travis/build/PyO3/pyo3/examples/rustapi_module/.tox/.package/lib/python3.8/site-packages/setuptools/command/sdist.py", line 54, in run
    self.make_distribution()
  File "/home/travis/build/PyO3/pyo3/examples/rustapi_module/.tox/.package/lib/python3.8/site-packages/setuptools/command/sdist.py", line 78, in make_distribution
    orig.sdist.make_distribution(self)
  File "/opt/python/3.8.0/lib/python3.8/distutils/command/sdist.py", line 473, in make_distribution
    self.make_release_tree(base_dir, self.filelist.files)
  File "setup.py", line 47, in make_release_tree
    cargo_toml = toml.load(f)
  File "/home/travis/build/PyO3/pyo3/examples/rustapi_module/.tox/.package/lib/python3.8/site-packages/toml/decoder.py", line 110, in load
    if _ispath(f):
  File "/home/travis/build/PyO3/pyo3/examples/rustapi_module/.tox/.package/lib/python3.8/site-packages/toml/decoder.py", line 29, in _ispath
    return _detect_pathlib_path(p)
  File "/home/travis/build/PyO3/pyo3/examples/rustapi_module/.tox/.package/lib/python3.8/site-packages/toml/decoder.py", line 20, in _detect_pathlib_path
    import pathlib
  File "/opt/python/3.8.0/lib/python3.8/pathlib.py", line 391, in <module>
    class _NormalAccessor(_Accessor):
  File "/opt/python/3.8.0/lib/python3.8/pathlib.py", line 415, in _NormalAccessor
    link_to = os.link
AttributeError: module 'os' has no attribute 'link'

[programmerjake]

seems like a messed up python build to me. Try using a different python 3.8 build.

Alternatively, something could be messing up the os module or aliasing it (not sure if either of those could be done in Python).