virtualenv v20 breaks poetry (and presumably untold other software)

[Drarok]

Issue

Poetry is a dependency and packaging management tool which is seemingly broken by virtualenv v20.

I'm a user of CircleCI who appear to have updated their base images to use the latest version of virtualenv which causes poetry to break.

Environment

Provide at least:

• OS: CircleCI Python images
• pip list: unavailable

Output seen when attempting to install dependencies

$ poetry install
Installing dependencies from lock file
[ImportError]
cannot import name create_environment

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I would expect a breaking change like this to first issue deprecation warnings before removing an object/import/etc.

[gaborbernat]

We've been following semantic versioning, so as such version 16 did not break API. A new major version can introduce breaking change. It's not our fault that poetry does not pin correctly it's dependencies.