bff6c67911
When installing many python packages, a `direct_url.json` file appeared in the lib directory. Example:
```sh
➤ nix build nixpkgs/29755fec55e58a315b517d431b2be261772f2b80#python3Packages.flask
➤ cat result/lib/python3.10/site-packages/Flask-2.2.3.dist-info/direct_url.json
{"archive_info": {}, "url": "file:///build/Flask-2.2.3/dist/Flask-2.2.3-py3-none-any.whl"}⏎
```
As you can see, that file contains a wrong reference to `/build`.
In https://discuss.python.org/t/pep-610-usage-guidelines-for-linux-distributions/4012/4 there's an explanation on how to avoid this. Here, I'm implementing that change for nixpkgs.
@moduon MT-1075