lock command hangs

Describe the bug

Hi there!

I maintain the Python Package Manager Shootout.

It benchmarks popular Python package managers in a common set of tasks. As of yesterday, the pdm task started timing out after 6 hours on the "lock cold" task: https://github.com/lincolnloop/python-package-manager-shootout/actions/runs/19102887872/job/54579026426

To reproduce

curl -sL requirements.txt https://raw.githubusercontent.com/getsentry/sentry/51281a6abd8ff4a93d2cebc04e1d5fc7aa9c4c11/requirements-base.txt | grep -v -- --index-url > requirements.txt
pdm import -f requirements ../requirements.txt
rm -rf ~/.cache/pip
rm -rf ~/.cache/pdm
rm -rf pdm/.venv pdm/__pypackages__
mkdir -p pdm/__pypackages__
rm -f pdm/pdm.lock
cd pdm; pdm lock

Expected Behavior

It used to finish in ~2 minutes

Environment Information

GitHub Actions with PDM installed via curl -sSL https://raw.githubusercontent.com/pdm-project/pdm/main/install-pdm.py | python3 -

Verbose Command Output

No response

Additional Context

All code is open source and available at https://github.com/lincolnloop/python-package-manager-shootout

Are you willing to submit a PR to fix this bug?

• Yes, I would like to submit a PR.