pip no longer prompts for user credentials

Description

When installing from an index url containing environment variables for user authentication, pip no longer prompts for credentials in case the environment variables aren’t set. This used to work up until v20.3.4.

Note: In our particular use case, packages are located on artifactory which returns 404 rather than 401 in case of incorrect credentials. Keyring is not an option since this needs to work in different environments where no keyring might be available.

Expected behavior

If environment variables needed for user authentication aren’t set, pip should prompt for credentials.

pip version

21.1.1

Python version

3.6.9

OS

Ubuntu 18.04 LTS

How to Reproduce

This works for pip version <= 20.3.4:

> echo $USER

> echo $PASSWORD

> pip install -i https://${USER}:${PASSWORD}@my.private.index -r requirements.txt
Looking in indexes: https://:****@my.private.index
User for my.private.index:

Instead now I get this:

> echo $USER

> echo $PASSWORD

> pip install -i https://${USER}:${PASSWORD}@my.private.index -r requirements.txt
Looking in indexes: https://:****@my.private.index
ERROR: Could not find a version that satisfies the requirement XXX

Output

No response

Code of Conduct

• I agree to follow the PSF Code of Conduct.

[uranusjr]

url: https://:@foo.com/

While there’s been a unintended change in behaviour here, I’m not sure that the older behaviour was correct even.

I wouldn’t even say it’s unintended. This is similar to the https://[e-mail] vs https://foo:@example.com debate we had in another issue; a blank username/password is not the same as not providing a username/password (according to how Basic Authentication is defined), so they should be treated differently.

[uranusjr]

I think it’s correct to not prompt. You supplied a username/password pair with foo:, so when that fails to authenticate, pip is expected to fail as in all other cases when a username/password pair is suplied. If you want pip to prompt for a password, you should not write that :.