The contents of this directory are extracted from virtualenv.pyz as downloaded
from https://bootstrap.pypa.io/virtualenv.pyz.

The virtualenv.py script is a wrapper that should be preserved and allows to
use the extracted virtualenv.pyz as-is.

It is not vendored via `mach vendor` because that would require a larger wrapper
script that handles the same things as the zipapp already does, picking the right
dependencies to add to the PYTHONPATH depending on the python version.