title: tox tests on python 2.7 -> ImportError: cannot import name ThreadingTCPServer
body: <p>Running tox on my python project I receive the following error:</p>
  <pre><code>ERROR: invocation failed (exit code 1), logfile: /home/project/.tox/py27/log/py27-2.log
  ============================================================================================================= log start ==============================================================================================================
  DEPRECATION: Python 2.7 reached the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 is no longer maintained. pip 21.0 will drop support for Python 2.7 in January 2021. More details about Python 2 support in pip can be found at https://pip.pypa.io/en/latest/development/release-process/#python-2-support
  Processing ./.tox/.tmp/package/1/hpecp-0.7.12.zip
    Installing build dependencies: started
    Installing build dependencies: finished with status 'error'
    ERROR: Command errored out with exit status 1:
     command: /home/project/.tox/py27/bin/python /home/project/.tox/py27/lib/python2.7/site-packages/pip install --ignore-installed --no-user --prefix /tmp/pip-build-env-UBlzBQ/overlay --no-warn-script-location --no-binary :none: --only-binary :none: -i https://pypi.org/simple -- 'setuptools&gt;=40.8.0' wheel
         cwd: None
    Complete output (22 lines):
    Traceback (most recent call last):
      File &quot;/home/theia/.pyenv/versions/2.7.18/lib/python2.7/runpy.py&quot;, line 174, in _run_module_as_main
        &quot;__main__&quot;, fname, loader, pkg_name)
      File &quot;/home/theia/.pyenv/versions/2.7.18/lib/python2.7/runpy.py&quot;, line 72, in _run_code
        exec code in run_globals
      File &quot;/home/project/.tox/py27/lib/python2.7/site-packages/pip/__main__.py&quot;, line 26, in &lt;module&gt;
        sys.exit(_main())
      File &quot;/home/project/.tox/py27/lib/python2.7/site-packages/pip/_internal/cli/main.py&quot;, line 73, in main
        command = create_command(cmd_name, isolated=(&quot;--isolated&quot; in cmd_args))
      File &quot;/home/project/.tox/py27/lib/python2.7/site-packages/pip/_internal/commands/__init__.py&quot;, line 104, in create_command
        module = importlib.import_module(module_path)
      File &quot;/home/theia/.pyenv/versions/2.7.18/lib/python2.7/importlib/__init__.py&quot;, line 37, in import_module
        __import__(name)
      File &quot;/home/project/.tox/py27/lib/python2.7/site-packages/pip/_internal/commands/install.py&quot;, line 17, in &lt;module&gt;
        from pip._internal.cli.req_command import RequirementCommand, with_cleanup
      File &quot;/home/project/.tox/py27/lib/python2.7/site-packages/pip/_internal/cli/req_command.py&quot;, line 13, in &lt;module&gt;
        from pip._internal.cli.base_command import Command
      File &quot;/home/project/.tox/py27/lib/python2.7/site-packages/pip/_internal/cli/base_command.py&quot;, line 6, in &lt;module&gt;
        import logging.config
      File &quot;/home/theia/.pyenv/versions/2.7.18/lib/python2.7/logging/config.py&quot;, line 46, in &lt;module&gt;
        from SocketServer import ThreadingTCPServer, StreamRequestHandler
    ImportError: cannot import name ThreadingTCPServer
    ---------------------------------------
  ERROR: Command errored out with exit status 1: /home/project/.tox/py27/bin/python /home/project/.tox/py27/lib/python2.7/site-packages/pip install --ignore-installed --no-user --prefix /tmp/pip-build-env-UBlzBQ/overlay --no-warn-script-location --no-binary :none: --only-binary :none: -i https://pypi.org/simple -- 'setuptools&gt;=40.8.0' wheel Check the logs for full command output.
  </code></pre>
  <p>My tox.ini</p>
  <pre><code>[tox]
  envlist = py27, py35, py36, py37, py38, py39
  skip_missing_interpreters = True
  
  [gh-actions]
  python =
      2.7: py27
      3.5: py35
      3.6: py36
      3.7: py37
      3.8: py38
  
  [testenv]
  commands = nosetests {posargs}
  deps =
      future
      jinja2
      mock
      nose
      requests
  setenv = TOX_BUILD_DIR = {toxinidir}
  
  [pytest]
  addopts = -s
  </code></pre>
  <p>All of the other python versions work ok.</p>