`pip freeze`: WARNING: Could not find setup.py for directory

[bhrutledge]

Description

In pypa/twine#757, I removed setup.py, because it was my understanding that it's no longer necessary for editable installs with recent versions of pip and setuptools. However, when I get a warning about that when I run pip freeze:

Expected behavior

If it's okay to omit setup.py, then I wouldn't expect a warning.

pip version

21.1.2

Python version

3.9.5

OS

macOS 11.3.1

How to Reproduce

% source /tmp/venv-twine/bin/activate

% pip install -e ~/Dev/twine
...
Installing collected packages: pyparsing, zipp, webencodings, urllib3, six, packaging, idna, chardet, certifi, requests, Pygments, importlib-metadata, docutils, bleach, tqdm, rfc3986, requests-toolbelt, readme-renderer, pkginfo, keyring, colorama, twine
  Running setup.py develop for twine
Successfully installed Pygments-2.9.0 bleach-3.3.0 certifi-2021.5.30 chardet-4.0.0 colorama-0.4.4 docutils-0.17.1 idna-2.10 importlib-metadata-4.5.0 keyring-23.0.1 packaging-20.9 pkginfo-1.7.0 pyparsing-2.4.7 readme-renderer-29.0 requests-2.25.1 requests-toolbelt-0.9.1 rfc3986-1.5.0 six-1.16.0 tqdm-4.61.1 twine-3.4.2.dev10+g6e8f187 urllib3-1.26.5 webencodings-0.5.1 zipp-3.4.1

% pip freeze
WARNING: Could not find setup.py for directory /Users/bhrutledge/Dev/twine (tried all parent directories)
bleach==3.3.0
certifi==2021.5.30
...
-e git+git@github.com:bhrutledge/twine.git@6e8f187947a0a23d3ca0daa6e88e19c7fd63fc77#egg=twine
...

Output

No response

Code of Conduct

• I agree to follow the PSF Code of Conduct.

[bhrutledge]

Thanks @uranusjr!