virtualenv can't be established on Python 3.5 since the last update

See the following log from our Windows tests: https://ci.appveyor.com/project/ladsgroup/pywikibot-g4xqx/build/job/w3ygc2f3winb4nnb

$ pip install virtualenv
Collecting virtualenv
  Downloading https://files.pythonhosted.org/packages/c1/61/7506ddd79ef6f09beeefb81c4c55bf395a8ad96b33ff1c6b06e40f8aa101/virtualenv-20.0.7-py2.py3-none-any.whl (8.0MB)
Collecting filelock<4,>=3.0.0 (from virtualenv)
  Downloading https://files.pythonhosted.org/packages/93/83/71a2ee6158bb9f39a90c0dea1637f81d5eef866e188e1971a1b1ab01a35a/filelock-3.0.12-py3-none-any.whl
Collecting distlib<1,>=0.3.0 (from virtualenv)
  Downloading https://files.pythonhosted.org/packages/7d/29/694a3a4d7c0e1aef76092e9167fbe372e0f7da055f5dcf4e1313ec21d96a/distlib-0.3.0.zip (571kB)
Collecting six<2,>=1.9.0 (from virtualenv)
  Downloading https://files.pythonhosted.org/packages/65/eb/1f97cb97bfc2390a276969c6fae16075da282f5058082d4cb10c6c5c1dba/six-1.14.0-py2.py3-none-any.whl
Collecting importlib-metadata<2,>=0.12 (from virtualenv)
  Downloading https://files.pythonhosted.org/packages/8b/03/a00d504808808912751e64ccf414be53c29cad620e3de2421135fcae3025/importlib_metadata-1.5.0-py2.py3-none-any.whl
Collecting appdirs<2,>=1.4.3 (from virtualenv)
  Downloading https://files.pythonhosted.org/packages/56/eb/810e700ed1349edde4cbdc1b2a21e28cdf115f9faf263f6bbf8447c1abf3/appdirs-1.4.3-py2.py3-none-any.whl
Collecting importlib-resources<2,>=1.0 (from virtualenv)
  Downloading https://files.pythonhosted.org/packages/a4/23/ffca4a0003519a156b178b3edd98ac9c9de051af76a993d15ed19862ea4d/importlib_resources-1.1.0-py2.py3-none-any.whl
Collecting zipp>=0.5 (from importlib-metadata<2,>=0.12->virtualenv)
  Downloading https://files.pythonhosted.org/packages/6f/6d/a55f6e81ac213942b9a19cbc05b560c726c3e16f8fb17555f059c17d65f2/zipp-3.0.0-py3-none-any.whl
Installing collected packages: filelock, distlib, six, zipp, importlib-metadata, appdirs, importlib-resources, virtualenv
  Running setup.py install for distlib
Successfully installed appdirs-1.4.3 distlib-0.3.0 filelock-3.0.12 importlib-metadata-1.5.0 importlib-resources-1.1.0 six-1.14.0 virtualenv-20.0.7 zipp-3.0.0
You are using pip version 7.1.2, however version 20.0.2 is available.
You should consider upgrading via the 'python -m pip install --upgrade pip' command.
$ virtualenv env
ImportError: cannot import name 'ContextManager'