`uv pip install` gets stuck combining `--resolution=lowest-direct` and `--upgrade` flags

Tested with `uv 0.1.3`.

Choose a package, in this example, `mypy`.

Run:

```
uv pip install --resolution=lowest-direct --upgrade "mypy"
```

This stalls for at least 30 minutes.

Seen on macOS (locally) and on Ubuntu (GitHub Actions).