The new caravel instruction "git clone -b mpw-7a <your github repo URL> caravel_example" is not working.

This may be because I suggested that you didn't need to include all branches. Try this from your shell

git clone -b mpw-7a <https://github.com/efabless/caravel.git> my_chip
cd my_chip
git remote rename origin upstream
git remote add origin <https://github.com/alokerdas/uP16_efabless.git>