Document PIP_REQUIRE_VIRTUALENV and --require-venv

[brettcannon]

Description

The documentation does not seem to mention PIP_REQUIRE_VIRTUALENV or --require-venv anywhere.

Expected behavior

No response

pip version

20.3.3

Python version

3.9

OS

Linux

How to Reproduce

Search for PIP_REQUIRE_VIRTUALENV in the docs or this repo.

Output

No response

Code of Conduct

• I agree to follow the PSF Code of Conduct.

[DiddiLeija]

You're right. The documentation only talks about a bug fix related to PIP_REQUIRE_VIRTUALENV, and that's all. Maybe we should add a document to explain this

[DiddiLeija]

Let's consider this as a feature request, since it is not a "bug" at all.

[jefftriplett]

@brettcannon @DiddiLeija should this still be open? #10588 helps with half the original bug/feature requests but PIP_REQUIRE_VIRTUALENV is still largely undocumented.

[uranusjr]

I think we can merge that part into #8044 since pip's environment variables are largely undocumented and this is only one more of them.