Can not install Poetry on Ubuntu 20.04

Reproduce the curl -sSL https://install.python-poetry.org | python3 - command with Python 3.8 on Ubuntu 20.04, then follow the installer traceback through main, install, and make_env. Investigate why the bundled virtualenv cannot load virtualenv.activation.xonsh; done means Poetry installs successfully in the reported environment without that ModuleNotFoundError.

Python 3.8

$ curl -sSL https://install.python-poetry.org | python3 -

Retrieving Poetry metadata

# Welcome to Poetry!

This will download and install the latest version of Poetry,
a dependency and package manager for Python.

It will add the `poetry` command to Poetry's bin directory, located at:

/home/.../.local/bin

You can uninstall at any time by executing this script with the --uninstall option,
and these changes will be reverted.

Installing Poetry (1.3.1): Creating environment
Poetry installation failed.
See /home/.../projects/poetry-installer-error-333ykixc.log for error logs.

$ cat /home/.../projects/poetry-installer-error-333ykixc.log

Traceback (most recent call last):
  File "/usr/lib/python3.8/runpy.py", line 194, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/lib/python3.8/runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "/tmp/poetry-installerowd8qj5i/virtualenv.pyz/__main__.py", line 167, in <module>
  File "/tmp/poetry-installerowd8qj5i/virtualenv.pyz/__main__.py", line 163, in run
  File "/tmp/poetry-installerowd8qj5i/virtualenv.pyz/virtualenv/__main__.py", line 16, in run
  File "/tmp/poetry-installerowd8qj5i/virtualenv.pyz/virtualenv/run/__init__.py", line 28, in cli_run
  File "/tmp/poetry-installerowd8qj5i/virtualenv.pyz/virtualenv/run/__init__.py", line 46, in session_via_cli
  File "/tmp/poetry-installerowd8qj5i/virtualenv.pyz/virtualenv/run/__init__.py", line 74, in build_parser
  File "/tmp/poetry-installerowd8qj5i/virtualenv.pyz/virtualenv/run/plugin/activators.py", line 11, in __init__
  File "/tmp/poetry-installerowd8qj5i/virtualenv.pyz/virtualenv/run/plugin/base.py", line 44, in options
  File "/tmp/poetry-installerowd8qj5i/virtualenv.pyz/virtualenv/run/plugin/base.py", line 23, in entry_points_for
  File "/tmp/poetry-installerowd8qj5i/virtualenv.pyz/virtualenv/run/plugin/base.py", line 23, in <genexpr>
  File "/usr/lib/python3.8/importlib/metadata.py", line 77, in load
    module = import_module(match.group('module'))
  File "/usr/lib/python3.8/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 973, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'virtualenv.activation.xonsh'

Traceback:

  File "<stdin>", line 919, in main
  File "<stdin>", line 550, in run
  File "<stdin>", line 571, in install
  File "/usr/lib/python3.8/contextlib.py", line 113, in __enter__
    return next(self.gen)
  File "<stdin>", line 643, in make_env
  File "<stdin>", line 629, in make_env
  File "<stdin>", line 333, in make
  File "<stdin>", line 357, in run