User-Agent:       Mozilla/5.0 (X11; Linux x86_64; rv:94.0) Gecko/20100101
Firefox/94.0
Build Identifier: 

Poetry crashes while trying to install something in a virtualenv

Reproducible: Always

Steps to Reproduce:
1. poetry new foo
2. cd foo
3. poetry add black

Actual Results:  
Using version ^21.11b1 for black

Updating dependencies
Resolving dependencies... (0.7s)

Writing lock file

Package operations: 16 installs, 0 updates, 0 removals

  ��������� Installing pyparsing (3.0.6): Failed

  EnvCommandError

  Command
['/home/<user>/.cache/pypoetry/virtualenvs/foo-4uHc0o_q-py3.8/bin/python', '-']
errored with the following return code 1, and output: 
  Traceback (most recent call last):
    File "<stdin>", line 23, in <module>
  ImportError: attempted relative import with no known parent package
  input was : (followed by what seems to be the content of
/usr/lib/python3.8/site-packages/packaging/tags.py)


  at /usr/lib/python3.8/site-packages/poetry/utils/env.py:1180 in _run
      1176���������                 output = subprocess.check_output(
      1177���������                     cmd, stderr=subprocess.STDOUT, **kwargs
      1178���������                 )
      1179���������         except CalledProcessError as e:
    ��������� 1180���������             raise EnvCommandError(e, input=input_)
      1181��������� 
      1182���������         return decode(output)
      1183��������� 
      1184���������     def execute(self, bin, *args, **kwargs):


Failed to add packages, reverting the pyproject.toml file to its original
content.


Expected Results:  
Poetry is able to add `black` to pyproject.toml, and install it in a
virtualenv.