This is a known issue, you should downgrade pip to <20:
python -m pip install -U 'pip<20'
EDIT: This has been fixed in Panda3D, please update your version of Panda3D instead if you are experiencing this issue.
This is a known issue, you should downgrade pip to <20:
python -m pip install -U 'pip<20'
EDIT: This has been fixed in Panda3D, please update your version of Panda3D instead if you are experiencing this issue.